The only elements that are liquid at room temperature are bromine and mercury. However, you can melt gallium by holding a lump in the warmth of your hand.
Unlike many substances, water expands as it freezes. An ice cube takes up about 9% more volume than the water used to make it.
If you pour a handful of salt into a full glass of water, the water level will actually go down rather than overflowing the glass.
There is about 1/2 lb or 250 g of salt (NaCl) in the average adult human body.
A pure element can take many forms. For example, diamond and graphite both are forms of pure carbon.
The chemical name for water (H2O) is dihydrogen monoxide.
The only letter that doesn't appear on the periodic table is J.
Lightning strikes produce O3, which is ozone, and strengthen the ozone layer of the atmosphere.
The only two non-silvery metals are gold and copper.
Although oxygen gas is colorless, the liquid and solid forms of oxygen are blue.
The human body contains enough carbon to provide 'lead' (which is really graphite) for about 9,000 pencils.
Hydrogen is the most abundant element in the universe, while oxygen is the most abundant element in the earth's atmosphere, crust, and oceans (about 49.5%).
The rarest naturally-occurring element in the earth's crust may be astatine. The entire crust appears to contain about 28 g of the element.
Hydrofluoric acid is so corrosive that it will dissolve glass. Although it is corrosive, hydrofluoric acid is considered to be a 'weak acid'.
One bucket full of water contains more atoms than there are bucketfuls of water in the Atlantic ocean.
Approximately 20% of the oxygen in the atmosphere was produced by the Amazon rainforest.
Helium balloons float because helium is lighter than air.
Bee stings are acidic while wasp stings are alkaline.
Hot peppers get their heat from a molecule called capsaicin. While the molecule acts as an irritant to mammals, including humans, birds lack the receptor responsible for the effect and are immune to the burning sensation from exposure.
Dry ice is the solid form of carbon dioxide, CO2.
Liquid air has a bluish tint, similar to water.
Atmosphere
ReplyDeleteOxygen is not the most abundant element in our atmosphere. The most abundant element is Nitrogen, 78% while Oxygen is 21% and Argon is just short of 1%. Carbon Dioxide and trace elements make up the rest.
Pade MkiPost daw dgdi sa POST mo eu?!!??
Deleteonly elements that are liquid at room temperature are bromine and mercury. However, you can melt gallium by holding a lump in the warmth of your hand.
Unlike many substances, water expands as it freezes. An ice cube takes up about 9% more volume than the water used to make it.
If you pour a handful of salt into a full glass of water, the water level will actually go down rather than overflowing the glass.
There is about 1/2 lb or 250 g of salt (NaCl) in the average adult human body.
http://chemistry.about.com/od/chemistryforkids/a/Fun-And-Interesting-Chemistry-Facts.htm
Fastest Half-Life
ReplyDeleteBerrylium-8 has the shortest half-life, 70 x 10^-18 seconds, or 0.000000000000000070 seconds.
Very Cold!
The lowest temperature reached in the laboratory is 7 nanokelvins, very near to absolute zero. The temperature was reached when helium was cooled to become a superfluid -- a fluid that could defy gravity.
Cops and Copper
Cops got the nickname because buttons on their uniforms use to be made of copper metal. In England, policemen were nicknamed "coppers" and the US has shortened this to "cops."
Graphite
Graphite can be transformed into diamond by applying a temperature of 3000°C and pressure of 100,000 atm
William Jefferson poh 2 sir!!
ginamit q poh kay MILLARD kc d aq naka register!!
Have you ever unintentionally burnt a slice of bread in the toaster? The blackness you notice over the burnt bread is because of the traces of burnt carbon. Carbon exists in both mineral form (such as coal, diamond, carbon dioxide in das form or dissolved in water) and in organic form.
ReplyDeleteFOUR MAJOR SOURCES OF CARBON PRESENT ON EARTH
Atmosphere: Carbon dioxide
Hydrosphere: Carbon dioxide, bicarbonate
Lithosphere: Petroleum, coal, natural gas, carbon
Biosphere: Organic molecules within the organism
Most of the carbon in the nature is present in the form of carbon dioxide. The carbon from the carbon dioxide is very significant for photosynthesis. The carbon dioxide in air is used in the process of photosynthesis together with water and nutritional salts.
Organic carbon, which is the building block of living organisms, is generated through the process of photosynthesis from the carbon dioxide gas available in the atmosphere or dissolved in the sea water.
Green plants, animal and vegetal parasites recycle carbon into carbon dioxide gas by decomposing organic matter. The residues, feces and corpses also decompose recycling the carbon dioxide present in their structure.
As seen in the figure, carbon dioxide that is present in the atmosphere in gas form and in the hydrosphere in dissolved form is the main source of carbon for living organisms. A part of the carbon within the animal body is recycled back into the atmosphere as CO2 through respiration in the mitochondrion.
Food + Oxygen --> Water + Carbon dioxide + Energy
(Mitochondrion)
The carbon in the remains and the wastes of all organisms is released back in the form of CO2 following a series of events such as putrefaction and decomposition – Fermentation.
A portion of the organic carbon is accumulated in fossil fuels such as coal and petroleum. An abundant amount of carbon dioxide is released into the atmosphere through their combustion. A major portion of this is rapidly transferred into the seas and the oceans and is accumulated in the form of carbonates. Additionally, volcanic eruptions also release a considerable amount of carbon dioxide into the atmosphere.
Daily Life Informtaion Regarding The Carbon Cycle
The carbon cycle takes place among the atmosphere, lithosphere, hydrosphere and the biosphere. Unless the cycle is interrupted, the carbon is present in equilibrium in the nature. The amount of CO2 in the atmosphere is fixed and known. If the CO2 taken from the atmosphere were not released back, photosynthetic processes would be reduced gradually and in approximately 35 years, the life as we know would cease on earth as the food chain would be broken. The carbon balance in the atmosphere is also interrupted through the negative effects of man. The amount of carbon dioxide fed into the atmosphere has increased by 25% as a result of industrialization.
The carbon dioxide present in the atmosphere and the water are in equilibrium. The natural source of carbon dioxide in the lithosphere is the volcanoes. Mankind mines and utilizes the fossil fuels more as a result of rapid industrialization, urbanization and population rise. The amount of carbon dioxide released into the atmosphere is increased as a result of the combustion of limestone and fossil fuels such as coal, natural gas and petroleum.
The depletion of the natural vegetation on earth (as a result of forest fires, for instance) also affects the carbon balance significantly. This situation clearly states that the carbon cycle can be altered by artifact causes. The increasing amount of carbon dioxide in the atmosphere will result in an increase of a couple of degrees in the temperature of the earth. As the earth surface gets warmer, the sea level will increase through melting of the glaciers and the earth climate will be altered.
This comment has been removed by the author.
ReplyDeleteHere’s your daily dose of Chemistry related trivia… actually biochemistry trivia today. You hear the term carbohydrate all the time, but where did the term carbohydrate come from?
ReplyDeleteIn organic chemistry there are groups of certain atoms referred to as functional groups. These functional groups are usually attached to at least one carbon atom and help give a molecule it’s name. For example, -PO43- is called a phosphate. Hence the name of H12N3O4P, a common ingredient in fertilizer, is named ammonium phosphate.
What does all this have to do with carbohydrates? A common base formula for simple sugars is CH2O. Therefore early scientists simple called sugars carbohydrates due to the H2O attached to the carbon atom.
Cool Chemistry Facts and Trivia
ReplyDeletechemistry bottlesHere are some interesting chemistry facts… who knows, you may some day be on jeopardy.
Glass is actually a liquid, it just flows very, very slowly. Same with asphalt.
In the early 1940s a large portion of the world’s plutonium supply was accidentally ingested by a lab technician. The majority of plutonium, like other heavy metals, passes right through your digestive tract. Don’t ask how they recovered all that plutonium…
Did your high school tell you there are three states of matter? Solid, liquid, gas. Or Maybe they threw in a fourth state, plasma. In fact, there are many more than just three or four states of matter. Around absolute zero a lot of funny things happen and new states of matter pop up, like Bose-Einstein condensates which defy gravity.
Watson and Crick, the co-discoverer’s of the DNA double helix never actually ran any experiments on their own, but rather read deeply into others’ work and deduced the structure.
Lithium can alter how you think and has been known to “cure” certain mental illnesses. In fact, lithium is used in a lot of psychoactive drugs.
One of the first x-rays, a picture you’ve probably seen of a woman’s hand with a ring on it, was of Bertha Rontgen’s hand. She thought seeing her bones was a death omen.
Hot water freezes quicker than cold water.
People used to drink radioactive water from a device called the “Revigator.” It was considered to be a healthy drink.
Diamonds aren’t the rarest gems on Earth. In fact, they’re relatively common. The rarest gem is jadeite and costs about $3 million per carat.
Only 28 grams of the rarest substance on Earth exist. What’s the rarest substance on Earth? Astatine.
Gallium, a metal element, will melt in your hand. You can even buy some here.
Liquid oxygen is blue.
The letter J is the only letter that doesn’t appear in the periodic table.
Every time lightening strikes, ozone is created.
This comment has been removed by the author.
ReplyDeleteThe eight 'Noble metals' — ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold — do not rust.
DeleteThe coldest state of matter — Bose-Einstein Condensate superfluid — defies gravity and instead of flowing down, it flows upward.
The noble gas Xenon lasers can cut through materials that are so tough even diamond tipped blades will not cut.
http://www.sciensational.com/chemistry.html
Oxygen is the most abundant element in the Earth's crust, waters, and atmosphere (about 49.5%)
ReplyDeleteThe only letter not appearing on the Periodic Table is the letter J.
Hydrofluoric acid will dissolve glass.
A bee sting is acidic and a wasp sting is alkali. To treat a sting by one of these you should use the opposite type of chemical.
The amount of carbon in the human body is enough to fill about 9,000 'lead' pencils.
litmus
ReplyDeleteRub the petals of a red chinarose on a piece of white paper and let it dry for two minutes in air. Now just put a single drop of lemon sap on it, you will see a color change from blue to red. Here you have made a litmus paper- a quick and simple way to test the presence of acid and base.
—Guest krishnendu
Atmosphere
Oxygen is not the most abundant element in our atmosphere. The most abundant element is Nitrogen, 78% while Oxygen is 21% and Argon is just short of 1%. Carbon Dioxide and trace elements make up the rest.
—Guest Matt
When the noble ones combine...
Xenon hexaflouroplatinate (XePtF6) is the first compound with a noble gas in it. It was first produced by Neil Bartlett in 1962.
Hi!
ReplyDeleteHers's your chemistry trivia 4 2day!
Henry Cavendish
....................not only discovered hydrogen, but also determined the mass of the Earth.
-http://www.juliantrubin.com/sciencetrivia/chmistrytrivia.html
Chemistry News :)
ReplyDeleteNew element to be added to periodic table
Last Updated: Thursday, June 11, 2009 | 3:56 PM ET
CBC News
Internal Links
U.S., Russian scientists find element 118Watch out, Superman! Kryptonite found on Earth
A new element is set to occupy spot 112 on the periodic table.(iStock)Scientists are about to add a new, super-heavy element to the periodic table.
"The new element is approximately 277 times heavier than hydrogen, making it the heaviest element in the periodic table," the German scientists who produced the element said in a statement on Wednesday.
The new element is massive and unstable — it can only exist for fractions of a second before splitting up in radioactive decay. It will occupy spot 112 on the periodic table. Elements are assigned numbers on the table based on how many protons they have.
The team of German researchers at the GSI Helmholtz Center for Heavy Ion Research produced the element for the first time a decade ago. The experiment that created it is very hard to duplicate, so it took years for the International Union of Pure and Applied Chemistry (IUPAC) to independently verify its existence.
The same team that produced element 112 is also responsible for adding elements 107-111 to the periodic table. Sigurd Hofmann, who led the team at the Centre for Heavy Ion Research, has been working on adding to the table since 1976.
Hofmann and his research team made element 112 by firing charged zinc atoms at lead atoms with a particle accelerator. The nuclei of the two atoms merged and immediately begin to decay. The researchers then calculated the size of the fused nucleus by measuring the amount of energy emitted by the decaying particle.
The team's next job is to propose a name for the element. This has to be done before it can be formally added to the periodic table.
Shortlist of potential names secret
For now, Hofmann is keeping the shortlist of potential names a secret. In the meantime, it will go by the temporary name ununbium, based on the Latin words for "one one two."
Creating new elements helps scientists understand nuclear power better, which could lead to advances in nuclear power and radioactive waste management, as well as nuclear weapons.
Research teams in the United States, Russia and Japan are also engaged in an unofficial race to discover new and heavier elements. Hoffman said he believed elements with as many as 120 protons can be produced.
Creating new elements helps scientists understand nuclear power better, which could lead to advances in nuclear power and radioactive waste management, as well as nuclear weapons.
The heaviest naturally occurring element is uranium, which has 92 protons. Scientists produced the first artificial element at the University of California, Berkeley in 1940. It had 93 protons and was named neptunium.
-http://www.cbc.ca/news/technology/story/2009/06/11/unnamed-element-periodic-table.html
Pick up line of the day!
ReplyDeletecheesy pick up line rather
If you were C6, and I were H12, all we would need is the air we breathe to be sweeter than sugar.
-http://pickuplinesgalore.com/biochem.html
Chemistry Facts & Trivia
ReplyDelete○ Astatine is the rarest element on Earth (approx 28g in the Earth's entire crust.)
Submitted by: Shubhu - Rourkela, India
○ Gold and Copper are the only two non-white metals.
○ Aluminium is the most common metal in the Earth's crust (8 percent of its weight.)
Submitted by: Moi - Toronto, Ontario, Canada
○ The element Californium is often called the most expensive substance in the world (as much as $68 million for one gram.)
Submitted by: Major Problem
○ The coldest state of matter — Bose-Einstein Condensate superfluid — defies gravity and instead of flowing down, it flows upward.
Submitted by: Moi - Toronto, Ontario, Canada
○ A bucket full of water contains more atoms than there are bucketfuls of water in the Atlantic Ocean.
Submitted by: Megan H - United States
○ Just one atomic layer thick, the 'miracle material' Graphene is a better conductor of electricity and heat than any material.
Submitted by: Vera - Sydney, Australia
○ Chalk is made of trillions of microscopic skeleton fossils of plankton (a tiny sea creature.)
Submitted by: Sam - Los Angeles, California, United States
○ The noble gas Xenon lasers can cut through materials that are so tough even diamond tipped blades will not cut.
Submitted by: Josh Davies - Llanelli, Wales
○ Twenty percent of Earth's oxygen is produced by the Amazon forest.
Submitted by: Jassim - Salem, India
○ Unlike any other element, helium does not solidify.
Submitted by: Abhi - India
○ Each time lightning strikes, some Ozone gas is produced, thus strengthening the Ozone Layer in the Earth's atmosphere.
○ Honey does not spoil.
Submitted by: Ashalaya - Racine, Wisconsin, United States
○ There's enough gold in the Earth's crust to cover the entire land surface knee-deep.
Source : http://www.sciensational.com/chemistry.html
Magnesium oxide might go metallic in super-Earths
ReplyDeleteWe take the Earth’s magnetic field for granted, but it is the only thing protecting us from the sun’s bombardment of lethal charged particles. Now, however, it seems there may be more planets outside our solar system with protective magnetic fields than previously thought. That’s the implication of a US study, which has demonstrated that the common planetary mineral magnesium oxide turns into a metallic liquid at high pressure.
Magnesium oxide is one of the simplest oxides present in terrestrial planets such as the Earth, as well as in the cores of giant planets such as Jupiter. Scientists are therefore keen to understand how its properties change under high temperatures and pressures. Theoretical predictions suggest that at very high pressures (0.3 to 0.7TPa) it should transform from a structure like sodium chloride, where each magnesium ion has six adjacent oxygen ions, to a structure like caesium chloride, where each magnesium ion has eight adjacent oxygen ions. Theory also predicts that at very high temperatures, typically greater than 5000K, magnesium oxide should turn into a liquid.
Unfortunately, current techniques have struggled to reach these pressures and temperatures. As a result, it has been impossible to map magnesium oxide’s actual phase changes. ‘Theorists have been publishing all these papers,’ says author Stewart McWilliams at Howard University in Washington, DC. ‘I think they’ve been desperate for some experiments!’
McWilliams’s group, which includes colleagues at the University of California at Berkeley and Lawrence Livermore National Laboratory, also in California, has managed to perform the necessary experiments using a shock-compression technique. The researchers blasted a small piece of magnesium oxide with high-powered lasers to generate pressures beyond 1.4TPa and temperatures of about 50,000 K. The blast sent a shockwave through the material, which the researchers monitored with a camera.
Shocking pressures
They found that the magnesium oxide changed from the NaCl-like structure to the CsCl-like structure at a pressure of 0.44TPa and a temperature of 9000K – broadly agreeing with the theoretical values of 0.33TPa and 8100 K, respectively. Meanwhile, the oxide changed into a metallic liquid at a pressure of 0.65TPa and a temperature of 14,000 K – again broadly agreeing with the theoretical values of 0.59 TPa and 13,600K.
The discovery of a liquid metallic state for magnesium oxide may not be surprising theoretically, but it does have ramifications for those studying planetary magnetic fields. The Earth’s own magnetic field – and that of Mercury, the only other rocky planet known to have a magnetic field – stems from the constant motion of its molten iron core, which generates a magnetic dynamo. If a rocky planet doesn’t have a moving, molten core, say many planetary scientists, it won’t have a magnetic field.
That picture may not be quite right though. A planet might not have a dynamo at its core, say McWilliams and colleagues, but it might have enough metallic magnesium oxide to perform the same function in its mantle – provided the temperature and pressure are high enough. Such conditions would probably be found inside ‘super-Earths’ – rocky planets with masses up to 15 times that of ours.
‘If you squeeze and heat hard and high enough, everything becomes metallic,’ says physicist Dario Alfè at University College London, UK. ‘The crucial point here is that magnesium oxide appears to become metallic at conditions not too far from those [at] the centre of terrestrial planets ... It makes super-Earths more likely to have magnetic fields, which [are] a protective shield from harmful solar (or stellar) radiation, and also make the retention of an atmosphere easier.’
REFERENCES
R S McWilliams et al, Science, 2012, DOI: 10.1126/science.1229450
source: http://www.rsc.org/chemistryworld/2012/11/super-earth-magnesium-oxide-liquid
nice information, it wold really helped other students especially those are researching for important chemical concepts. Just continue sharing and spreading the good news about chemstry
ReplyDeleteHi :)
ReplyDeletechemistry news for 2day!!!!
A Better Way to Make Chemicals? Technique for Observing 'Mechanochemical' Synthesis Could Boost Green Chemistry
ScienceDaily (Dec. 2, 2012) — Bulk solvents, widely used in the chemical industry, pose a serious threat to human health and the environment. As a result, there is growing interest in avoiding their use by relying on "mechanochemistry" -- an energy-efficient alternative that uses high-frequency milling to drive reactions. Because milling involves the intense impact of steel balls in rapidly moving jars, however, the underlying chemistry is difficult to observe.
Now, for the first time, scientists have studied a milling reaction in real time, using highly penetrating X-rays to observe the surprisingly rapid transformations as the mill mixed, ground, and transformed simple ingredients into a complex product. This research, reported Dec. 2 in Nature Chemistry, promises to advance scientists' understanding of processes central to the pharmaceutical, metallurgical, cement and mineral industries -- and could open new opportunities in "green chemistry" and environmentally friendly chemical synthesis.
The international team of researchers was led by Tomislav Friščić of McGill University in collaboration with Ivan Halasz from the University of Zagreb in Croatia, and scientists from the University of Cambridge, the Max-Planck-Institute for Solid State Research in Stuttgart, Germany, and the European Synchrotron Radiation Facility (ESRF) in Grenoble, France.
While mechanical action can break chemical bonds -- for example, in the wear and tear of textile fibers -- mechanical force can also be used to synthesize new chemical compounds and materials. In recent years, ball milling has become increasingly popular in the production of highly complex chemical structures. In such synthesis, steel balls are shaken with the reactants and catalysts in a rapidly vibrating jar. Chemical transformations take place at the sites of ball collision, where impact causes instant "hot spots" of localized heat and pressure. This is difficult to model and, without access to real time reaction monitoring, mechanochemistry remained poorly understood.
"When we set out to study these reactions, the challenge was to observe the entire reaction without disturbing it, in particular the short-lived intermediates that appear and disappear under continuous impact in less than a minute," says Friščić, an assistant professor in McGill's Department of Chemistry.
The team of scientists chose to study mechanochemical production of the metal-organic framework ZIF-8 from the simplest and non-toxic components. Materials such as ZIF-8 are rapidly gaining popularity for their ability to capture large amounts of CO2; if manufactured cheaply and sustainably, they could become widely used for carbon capture and storage, catalysis and even hydrogen storage.
"The team came to the ESRF because of our high-energy X-rays capable of penetrating 3 mm thick walls of a rapidly moving reaction jar made of steel, aluminium or plastic. The X-ray beam must get inside the jar to probe the mechanochemical formation of ZIF-8, and then out again to detect the changes as they happened," says Simon Kimber, a scientist at the European Synchrotron Radiation Facility (ESRF) in Grenoble, who is a member of the team. This unprecedented methodology enabled the real-time observation of reaction kinetics, reaction intermediates and the development of their respective nanoparticles.
In principle, this technique could be used to study all types of chemical reactions in a ball mill, and optimize them for processing in a range of industries. "That would translate into good news for the environment, for industry -- and for consumers," Friščić says.
Chemistry Facts!!
ReplyDelete:)
Chemistry Facts & Trivia
The eight 'Noble metals' — ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold — do not rust. Submitted by: Richard
Tabletop "volcanoes" can be created using 'Vesuvian Fire' compound Ammonium dichromate. Submitted by: Emily (Awesome) - Helena, Montana, United States
Just one atomic layer thick, the 'miracle material' Graphene is a better conductor of electricity and heat than any material. Submitted by: Vera - Sydney, Australia
Graphite can be transformed into diamond by applying a temperature of 3000°C and pressure of 100,000 atm. Submitted by: Hyde - Toronto, Ontario, Canada
The coldest state of matter — Bose-Einstein Condensate superfluid — defies gravity and instead of flowing down, it flows upward. Submitted by: Moi - Toronto, Ontario, Canada
The element Californium is often called the most expensive substance in the world (as much as $68 million for one gram.) Submitted by: Major Problem
Aluminium is the most common metal in the Earth's crust (8 percent of its weight.) Submitted by: Moi - Toronto, Ontario, Canada
Unlike any other element, helium does not solidify. Submitted by: Abhi - India
Hot water freezes faster than cold water (the Mpemba effect.) Submitted by: Moi - Toronto, Ontario, Canada
Astatine is the rarest element on Earth (approx 28g in the Earth's entire crust.) Submitted by: Shubhu - Rourkela, India
The six states of matter are: Plasmas, Gases, Liquids, Solids, Bose-Einstein Condensates and Fermionic Condensates. Submitted by: Adarsh - Jamshedpur, India & Amina Kunting - Antipolo, Philippines
Chalk is made of trillions of microscopic skeleton fossils of plankton (a tiny sea creature.) Submitted by: Sam - Los Angeles, California, United States
A bucket full of water contains more atoms than there are bucketfuls of water in the Atlantic Ocean. Submitted by: Megan H - United States
A rubber tire is actually one single giant molecule. Submitted by: Moi - Toronto, Ontario, Canada
Dynamite contains peanuts as an ingredient. Submitted by: Manaal - Dubai, United Arab Emirates
Talc is the softest known substance. Submitted by: Laine - United States
Gallium is a metal which melts on palm of the hand, due to its low melting point (29.76 °C). Submitted by: Karanpal Singh - Amritsar, India
Twenty percent of Earth's oxygen is produced by the Amazon forest. Submitted by: Jassim - Salem, India
The noble gas Xenon lasers can cut through materials that are so tough even diamond tipped blades will not cut. Submitted by: Josh Davies - Llanelli, Wales
Gold and Copper are the only two non-white metals.
........
ReplyDeletechemistry explains the world around you..
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kaya tnx to chemistry 4 making my life much clearer :)
and tnx for our wonderful and very smart teacher ......
Thanks for the complement
DeleteGood day readers!
ReplyDelete. . .
Chemistry is truly an interesting subject and because of it I can able to explain physical as well as biological aspects inner or outer parts of my body. I can also identify what is/are harmless or harmful substance/s surrounding my body. However I could also say that this subject is a little bit difficult if you are not so interested with it. Further research is a must to find the different formulas, properties, etc. But for me, although a found it also slightly difficult, I quite enjoying taking up this subject because of some reasons;First we had an outstanding teacher in the person of Mr. Ronaldo Reyes, who thought us different, interesting ideas about this subject and lastly this subject explains the hidden facts about different things that I never been encountered since before. In short, Chemistry as the central Science, explain its event in nature.
..
Further of this, I also searched for some trivia for chemistry.
*Trivia # 1:
What makes Chili peppers so hot?
>Some like it hot and if you’re one of them then you like capsaicin. It’s the chemical that makes your mouth burn when you eat chili peppers. Capsaicin causes this burning sensation in all mammals.
Plants produce capsaicin to protect their seeds from mammals that destroy their seeds when they eat the plant's fruit. When birds eat the fruit they don’t hurt the seeds, in fact they help the plant distribute them. So, it’s not a surprise that birds can’t sense capsaicin and aren’t bothered by it.
The seeds themselves don’t contain capsaicin. Instead its found in the “white” cross wall and veins of the pod and to a lesser extent the fleshy part.
The most scientific way to measure the hotness or piquancy of different chili peppers is to use high-performance liquid chromatography, but this method is more expensive than the older “Scoville” method. The Scoville method is more subjective and uses a group of taste testers (usually around 5) to rate the hotness.
Below is a chart showing the Scoville heat units for a variety of peppers
*Trivia # 2:
What two elements are named after women?
>Curium [Cm]– Named after Marie Skłodowska–Curie (and her husband Pierre Curie) in 1944. Marie Curie was a chemist who created the theory of radioactivity and along with here husband coined the term “radioactive”. Together they discovered two new elements, radium and polonium. Marie Curie is one of only four people to win two Nobel prizes.
Meitnerium [Mt] – Named after Lise Meitner in 1992. Lise Meiter was instrumental in the discovery of nuclear fission. Otto Hahn, her collaborator, was awarded the Nobel Prize for the discovery. Her contribution was overlooked by the committee.
A few mythical women are also represented on the periodic table.
Niobium [Nb] – Named after Niobe, a tragic mortal woman from Greek mythology.
Vanadium [V]– Named after the beautiful Scandinavian goddess Vanadis (a.k.a. Freyja). She was the is the goddess of love and fertility.
*Trivia #3:
What is sodium laureth sulfate?
>You've probably been spending way too much time in the bathtub if you're reading shampoo labels.
Sodium laureth sulfate is what puts the bubble in your shampoo. It’s a cheap foaming agent used in a wide variety of products including laundry detergent, bubble bath and hand soap.
Sodium laureth sulfate is a both a detergent and a surfactant. It’s a less harsh form of Sodium dodecyl sulfate (a.k.a. sodium lauryl sulfate). Still, studies have shown it can be irritating to the skin and eyes.
Source: http://www.just2smart.com/chemistry/
You've shared wonderful ideas about chemistry. Can you explain to the readers how spontaneous and nonspontaneous reactions take plce and can you give examples also?
ReplyDeleteSpontaneous process
DeleteTakes place ‘naturally’ with no apparent
cause or stimulus.
Nonspontaneous process
Requires that something be done in order
for it to occur.
Examples:
Spontaneous
Water freezes spontaneously below 0
0
C, and ice melts spontaneously above
0
0
C at 1 atm pressure (you see frost on your windshield on a cold night)
• Heat flows spontaneously from hotter object to colder object, but not other
way around (that is how your room gets heated in the winter time)
• A water fall (Niagara Falls or dams) runs spontaneously downhill, but never
uphill
• When you put a sugar in a cup of coffee, it dissolves spontaneously but it does
not reappear in its original form
• Rusting of iron nail when it exposed to moisture and oxygen is spontaneous.
So is tarnishing of the silverwares.
Non-Spontaneous
• recovery of metals from ore
• electroplating of surfaces
• recharging a battery.
that's all! :)
Do you know an interesting chemistry fact or are you looking for some cool chemistry trivia?
ReplyDelete*carbon
Car tires are black because they are about 30% carbon black , which is added to rubber to strengthen it . The carbon black also helps it to prevent against U.V. damage
*5 Phases
In the modern age, there are 5 known phases of matter, SOLID, LIQUID, GAS, PLASMA and BOSE EINSTEINIUM
*ionization potential
cesium has lowest ionization potential. because ionization potential decreases as the size of the element increases .so cesium being smaller than francium having the lowest ionization potential in the long form of periodic table,because francium is radio active .
*Name three allotropes of Carbon
Question: Name three allotropes of Carbon: Answer: Diamond, Graphite, and Fullerene...
*Tungsten(W)
Tungsten has highest m.p(3300centigrate).so it is used as a filament in bulb.
*mnemonic for organics
Most Electrons Prefer Bonding=MEPB= Methane Ethane Propane Butane
*litmus
Rub the petals of a red chinarose on a piece of white paper and let it dry for two minutes in air. Now just put a single drop of lemon sap on it, you will see a color change from blue to red. Here you have made a litmus paper- a quick and simple way to test the presence of acid and base.
*Atmosphere
Oxygen is not the most abundant element in our atmosphere. The most abundant element is Nitrogen, 78% while Oxygen is 21% and Argon is just short of 1%. Carbon Dioxide and trace elements make up the rest.
*When the noble ones combine...
Xenon hexaflouroplatinate (XePtF6) is the first compound with a noble gas in it. It was first produced by Neil Bartlett in 1962.
*Fastest Half-Life
Berrylium-8 has the shortest half-life, 70 x 10^-18 seconds, or 0.000000000000000070 seconds.
*Very Cold!
The lowest temperature reached in the laboratory is 7 nanokelvins, very near to absolute zero. The temperature was reached when helium was cooled to become a superfluid -- a fluid that could defy gravity.
*Cops and Copper
Cops got the nickname because buttons on their uniforms use to be made of copper metal. In England, policemen were nicknamed "coppers" and the US has shortened this to "cops."
*Giant Molecules
Rubber like you see on wheels of vehicles is actually one giant molecule.
*diamond
a diamond does not melt in acid.the only thing that can melt is the intense heat.
*PRABHAT (P+A)
red phosphorus is a non-metal. it is not malleable and forms acidic oxide.
URL:http://chemistry.about.com/u/ua/chemistrydatabases/Chemistry-Facts-And-Trivia.htm
Harold Urey and Deuterium January 5th marks the passing of Harold Urey. Urey was an American chemist who was awarded the 1934 Nobel Prize in Chemistry for his discovery of deuterium. Hydrogen is unique in that it has three isotopes which are named. Deuterium is one of the isotopes of hydrogen. It has one proton and one neutron. The most common isotope of hydrogen is protium, which has one proton and no neutrons. Because deuterium contains a neutron, it is more massive or heavier than protium, so it is sometimes called heavy hydrogen. Deuterium Facts
ReplyDeleteThe chemical symbol for deuterium is D. Sometimes the symbol 2H is used.
Deuterium is a stable isotope of hydrogen.
The natural abundance of deuterium in the ocean is approximately 156.25 ppm, which is one atom in 6,400 of hydrogen.
The name for deuterium comes from the Greek word deuteros, which means "second". This is in reference two the two particles, a proton and a neutron, which make up the nucleus of a deuterium atom.
A deuterium nucleus is termed a deuteron or deuton. Deuterium is an isotope of hydrogen. The most common form of hydrogen has one proton and no neutrons, but deuterium contains a proton and neutron in its nucleus. This isotope has the same chemical properties as hydrogen and can combine with oxygen to create water. Deuterium water is also known as 'heavy water'. Heavy water is used in many applications such as nuclear magnetic resonance, neutron moderation in nuclear power plants and organic chemistry.
Urey discovered deuterium by investigations of heavy water in 1931 and was important in the understanding of the concepts of isotopes.
http://chemistry.about.com/od/famouschemists/p/haroldclaytonureybio.htm
DeleteHi!
ReplyDeleteHers's your chemistry trivia 4 2day!
Henry Cavendish
....................not only discovered hydrogen, but also determined the mass of the Earth.
-http://www.juliantrubin.com/sciencetrivia/chmistrytrivia.html
Chemistry Facts!!
ReplyDelete:)
Chemistry Facts & Trivia
The eight 'Noble metals' — ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold — do not rust. Submitted by: Richard
Tabletop "volcanoes" can be created using 'Vesuvian Fire' compound Ammonium dichromate. Submitted by: Emily (Awesome) - Helena, Montana, United States
Just one atomic layer thick, the 'miracle material' Graphene is a better conductor of electricity and heat than any material. Submitted by: Vera - Sydney, Australia
Graphite can be transformed into diamond by applying a temperature of 3000°C and pressure of 100,000 atm. Submitted by: Hyde - Toronto, Ontario, Canada
The coldest state of matter — Bose-Einstein Condensate superfluid — defies gravity and instead of flowing down, it flows upward. Submitted by: Moi - Toronto, Ontario, Canada
The element Californium is often called the most expensive substance in the world (as much as $68 million for one gram.) Submitted by: Major Problem
Aluminium is the most common metal in the Earth's crust (8 percent of its weight.) Submitted by: Moi - Toronto, Ontario, Canada
Unlike any other element, helium does not solidify. Submitted by: Abhi - India
Cool Chemistry Facts and Trivia
ReplyDeleteHere are some interesting chemistry facts… who knows, you may some day be on jeopardy.
Glass is actually a liquid, it just flows very, very slowly. Same with asphalt.
In the early 1940s a large portion of the world’s plutonium supply was accidentally ingested by a lab technician. The majority of plutonium, like other heavy metals, passes right through your digestive tract. Don’t ask how they recovered all that plutonium…
Did your high school tell you there are three states of matter? Solid, liquid, gas. Or Maybe they threw in a fourth state, plasma. In fact, there are many more than just three or four states of matter. Around absolute zero a lot of funny things happen and new states of matter pop up, like Bose-Einstein condensates which defy gravity.
Watson and Crick, the co-discoverer’s of the DNA double helix never actually ran any experiments on their own, but rather read deeply into others’ work and deduced the structure.
Lithium can alter how you think and has been known to “cure” certain mental illnesses. In fact, lithium is used in a lot of psychoactive drugs.
One of the first x-rays, a picture you’ve probably seen of a woman’s hand with a ring on it, was of Bertha Rontgen’s hand. She thought seeing her bones was a death omen.
Hot water freezes quicker than cold water.
People used to drink radioactive water from a device called the “Revigator.” It was considered to be a healthy drink.
Diamonds aren’t the rarest gems on Earth. In fact, they’re relatively common. The rarest gem is jadeite and costs about $3 million per carat.
Only 28 grams of the rarest substance on Earth exist. What’s the rarest substance on Earth? Astatine.
Gallium, a metal element, will melt in your hand. You can even buy some here.
Liquid oxygen is blue.
The letter J is the only letter that doesn’t appear in the periodic table.
Every time lightening strikes, ozone is created.
^JOANNE BLANCA III-7^
ReplyDeleteChemistry is a fascinating science, full of unusual trivia! Here are some fun and interesting chemistry facts for you.
• The only elements that are liquid at room temperature arebromine and mercury. However, you can melt gallium by holding a lump in the warmth of your hand.
• Unlike many substances, water expands as it freezes. An ice cube takes up about 9% more volume than the water used to make it.
• If you pour a handful of salt into a full glass of water, the water level will actually go down rather than overflowing the glass.
• There is about 1/2 lb or 250 g of salt (NaCl) in the average adult human body.
• A pure element can take many forms. For example, diamond and graphite both are forms of pure carbon.
• The chemical name for water (H2O) is dihydrogen monoxide.
• The only letter that doesn't appear on the periodic table is J.
• Lightning strikes produce O3, which is ozone, and strengthen the ozone layer of the atmosphere.
• The only two non-silvery metals are gold and copper.
• Although oxygen gas is colorless, the liquid and solid forms of oxygen are blue.
• The human body contains enough carbon to provide 'lead' (which is really graphite) for about 9,000 pencils.
• Hydrogen is the most abundant element in the universe, while oxygen is the most abundant element in the earth's atmosphere, crust, and oceans (about 49.5%).
• The rarest naturally-occurring element in the earth's crust may be astatine. The entire crust appears to contain about 28 g of the element.
• Hydrofluoric acid is so corrosive that it will dissolve glass. Although it is corrosive, hydrofluoric acid is considered to be a 'weak acid'.
• One bucket full of water contains more atoms than there are bucketfuls of water in the Atlantic ocean.
• Approximately 20% of the oxygen in the atmosphere was produced by the Amazon rainforest.
• Helium balloons float because helium is lighter than air.
• Bee stings are acidic while wasp stings are alkaline.
• Hot peppers get their heat from a molecule called capsaicin. While the molecule acts as an irritant to mammals, including humans, birds lack the receptor responsible for the effect and are immune to the burning sensation from exposure.
• Dry ice is the solid form of carbon dioxide, CO2.
• Liquid air has a bluish tint, similar to water.
URL: http://chemistry.about.com/od/chemistryforkids/a/Fun-And-Interesting-Chemistry-Facts.htm
^KIM BERCES III-7^
ReplyDeleteSodium is an abundant element that is essential for human nutrition and important for many chemical processes. Here are 10 interesting facts about sodium.
1. Sodium is a silvery-white metal belonging to Group 1 of thePeriodic Table, which is the alkali metals group.
2. Sodium is highly reactive! The pure metal is kept under oil or kerosene because it spontaneously ignites in water. It's interesting to note, sodium metal also floats on water!
3. Room temperature sodium metal is soft enough that you can cut it with a butter knife.
4. Sodium is an essential element for animal nutrition. In humans, sodium is important for maintaining fluid balance in the cells and throughout the body. The electric potential maintained by sodium ions is critical for nerve function.
5. Sodium and it compounds are used for food preservation, cooling nuclear reactors, in sodium vapor lamps, to purify and refine other elements and compounds, and as a desiccant.
6. There is only one stable isotope of sodium, 23Na.
7. The symbol for sodium is Na, which comes from the Latin natrium or Arabic natrun or a similar-sounding Egyptian word, all referring to soda or sodium carbonate.
8. Sodium is an abundant element. It is found in the sun and many other stars. It is the 6th most abundant element on Earth, comprising about 2.6% of the earth's crust. It is the most abundant alkali metal.
9. Although it too reactive to occur in pure elemental form, it is found in many minerals, including halite, cryolite, soda niter, zeolite, amphibole, and sodalite. The most common sodium mineral is halite or sodium chloride salt.
10. Sodium first was commercially produced by by thermal reduction of sodium carbonate with carbon at 1100°C, in the Deville process. Pure sodium may be obtained by electrolysis of molten sodium chloride. It may be produced by by the thermal decomposition of sodium azide.
URL: http://chemistry.about.com/od/elementfacts/a/10-Sodium-Facts.htm
^AXEL ROY BELGADO III-7^
ReplyDeleteThis is a collection of 10 fun and interesting basic chemistry facts.
1. Chemistry is the study of matter and energy and the interactions between them. It is a physical science that is closely related to physics, which often shares the same definition.
2. Chemistry traces its roots back to the ancient study of alchemy. Chemistry and alchemy are separate now, though alchemy still is practiced today.
3. All matter is made up of the chemical elements, which are distinguished from each other by the numbers of protons they possess.
4. The chemical elements are organized in order of increasing atomic number into the periodic table. The first element in the periodic table is hydrogen.
5. Each element in the periodic table has a one or two letter symbol. The only letter in the English alphabet not used on the periodic table is J. The letter q only appears in the symbol for the placeholder name for element 114, ununquadium, which has the symbol Uuq. When element 114 is officially discovered, it will be given a new name.
6. At room temperature, there are only two liquid elements. These are bromine and mercury.
7. The IUPAC name for water, H2O, is dihydrogen monoxide.
8. Most elements are metals and most metals are silver-colored or gray. The only non-silver metals are gold and copper.
9. The discoverer of an element may give it a name. There are elements named for people (Mendelevium, Einsteinium), places (Californium, Americium) and other things.
10. Although you may consider gold to be rare, there is enough gold in the Earth's crust to cover the land surface of the planet knee-deep.
URL: http://chemistry.about.com/od/generalchemistry/a/10-Basic-Chemistry-Facts.htm
^IAN RAY BATALLA III-7^
ReplyDeleteHere are 10 fun and interesting facts about the element chromium.
1. Chromium has atomic number 24. It is the first element in Group 6 on the Periodic Table.
2. Chromium is a hard, lustrous, steel-gray metal.
3. Stainless steel is hard and resists corrosion due to the addition of chromium.
4. Chromium is the only element which shows antiferromagnetic ordering in its solid state at and below room temperature. Chromium becomes paramagnetic above 38°C.
5. Trace amounts of trivalent chromium are needed for lipid and sugar metabolism. Hexavalent chromium and its compounds are extremely toxic. The +1, +4 and +5 oxidation states also occur, although they are less common.
6. Chromium occurs naturally as a mix of three stable isotopes. 19 radioisotopes have been characterized.
7. Chromium is used to prepare pigments (including yellow, red and green), color glass green, color rubies red and emeralds green, in some tanning processes, as a decorative and protective metal coating and as a catalyst.
8. Chromium in air is passivated by oxygen, forming a protective layer that is essentially a spinel that is a few atoms thick.
9. Chromium is the 21st most abundant element in the Earth's crust. It is present at a concentration of approximately 100 ppm.
10. Most chromium is obtained by mining the mineral chromite. Although it is rare, native chromium also exists. It may be found in kimberlite pipe, where the reducing atmosphere favors the formation of diamond in addition to elemental chromium.
URL: http://chemistry.about.com/od/chromium/a/10-Chromium-Facts.htm
thre are several types of molecular geometry , trigonal pyramidal trigonal bpyramid ,octahedral,square pyramidal and square planar .a reaction is of a substance with another resulting in a chemical reactions are classified into four types the decompositions displacement and double displacement or double decomposition.thre is another type of chemical reaction the ovidation.
ReplyDeleteRub the petals of a red chinarose on a piece of white paper and let it dry for two minutes in air. Now just put a single drop of lemon sap on it, you will see a color change from blue to red. Here you have made a litmus paper- a quick and simple way to test the presence of acid and base.
ReplyDelete—Guest krishnendu
Atmosphere
Oxygen is not the most abundant element in our atmosphere. The most abundant element is Nitrogen, 78% while Oxygen is 21% and Argon is just short of 1%. Carbon Dioxide and trace elements make up the rest.
—Guest Matt
When the noble ones combine...
Xenon hexaflouroplatinate (XePtF6) is the first compound with a noble gas in it. It was first produced by Neil Bartlett in 1962.
Very Cold!
ReplyDeleteThe lowest temperature reached in the laboratory is 7 nanokelvins, very near to absolute zero. The temperature was reached when helium was cooled to become a superfluid -- a fluid that could defy gravity.
Atmosphere
ReplyDeleteOxygen is not the most abundant element in our atmosphere. The most abundant element is Nitrogen, 78% while Oxygen is 21% and Argon is just short of 1%. Carbon Dioxide and trace elements make up the rest.The chemical symbol for deuterium is D. Sometimes the symbol 2H is used.
Deuterium is a stable isotope of hydrogen.
The natural abundance of deuterium in the ocean is approximately 156.25 ppm, which is one atom in 6,400 of hydrogen.The six states of matter are: Plasmas, Gases, Liquids, Solids, Bose-Einstein Condensates and Fermionic Condensates. Submitted by: Adarsh - Jamshedpur, India & Amina Kunting - Antipolo, Philippines
Chalk is made of trillions of microscopic skeleton fossils of plankton (a tiny sea creature.) Submitted by: Sam - Los Angeles, California, United States
A bucket full of water contains more atoms than there are bucketfuls of water in the Atlantic Ocean. Submitted by: Megan H - United States
A rubber tire is actually one single giant molecule. Submitted by: Moi - Toronto, Ontario, Canada
Dynamite contains peanuts as an ingredient. Submitted by: Manaal - Dubai, United Arab Emirates
Talc is the softest known substance. Submitted by: Laine - United States
Gallium is a metal which melts on palm of the hand, due to its low melting point (29.76 °C). Submitted by: Karanpal Singh - Amritsar, India
Twenty percent of Earth's oxygen is produced by the Amazon forest. Submitted by: Jassim - Salem, India
The noble gas Xenon lasers can cut through materials that are so tough even diamond tipped blades will not cut. Submitted by: Josh Davies - Llanelli, Wales
Chemistry is a fascinating science, full of unusual trivia! Here are some fun and interesting chemistry facts for you.
ReplyDeleteThe only elements that are liquid at room temperature are bromine and mercury. However, you can melt gallium by holding a lump in the warmth of your hand.
Unlike many substances, water expands as it freezes. An ice cube takes up about 9% more volume than the water used to make it.
If you pour a handful of salt into a full glass of water, the water level will actually go down rather than overflowing the glass.
There is about 1/2 lb or 250 g of salt (NaCl) in the average adult human body.
A pure element can take many forms. For example, diamond and graphite both are forms of pure carbon.
The chemical name for water (H2O) is dihydrogen monoxide.
The only letter that doesn't appear on the periodic table is J.
Lightning strikes produce O3, which is ozone, and strengthen the ozone layer of the atmosphere.
The only two non-silvery metals are gold and copper.
Although oxygen gas is colorless, the liquid and solid forms of oxygen are blue.
The human body contains enough carbon to provide 'lead' (which is really graphite) for about 9,000 pencils.
Hydrogen is the most abundant element in the universe, while oxygen is the most abundant element in the earth's atmosphere, crust, and oceans (about 49.5%).
The rarest naturally-occurring element in the earth's crust may be astatine. The entire crust appears to contain about 28 g of the element.
Hydrofluoric acid is so corrosive that it will dissolve glass. Although it is corrosive, hydrofluoric acid is considered to be a 'weak acid'.
One bucket full of water contains more atoms than there are bucketfuls of water in the Atlantic ocean.
Approximately 20% of the oxygen in the atmosphere was produced by the Amazon rainforest.
Helium balloons float because helium is lighter than air.
Bee stings are acidic while wasp stings are alkaline.
Hot peppers get their heat from a molecule called capsaicin. While the molecule acts as an irritant to mammals, including humans, birds lack the receptor responsible for the effect and are immune to the burning sensation from exposure.
Dry ice is the solid form of carbon dioxide, CO2.
Liquid air has a bluish tint, similar to water.
URL:http://chemistry.about.com/od/chemistryforkids/a/Fun-And-Interesting-Chemistry-Facts.htm
^MARIA CARMINA BARRAMEDA^
ReplyDeleteHere is the chemistry trivia...
Graphite
Graphite can be transformed into diamond by applying a temperature of 3000°C and pressure of 100,000 atm
—Guest THE HELPER
lightning
Here is a chemistry fact/trivia: lightning is 3 times hotter than the sun.
—Guest krischa
Equation
Oxygen + Hydrogen= Hydrogen Oxide which is the same as water H20!
—Guest olivia
Lewis, Clark, and Mercury
Sam Kean in his book "The Disappearing Spoon" wrote that Lewis and Clark carried mercury laxatives with them on their famous trek. Today, archaeologists test the soil for mercury contamination to help identify their campsites.
—Guest Retired J.O.
Snowballs that burn
Under the right conditions, snow can form from hydrates instead of pure water. Hydrates are 3-dimensional crystalline structures that are stabilized by small molecules such as methane, ethane, propane, carbon dioxide, etc. Snowballs made from hydrates will actually burn due to the hydrocarbons trapped in their water crystals.
—Guest Margie
Carbon
A diamond and pencil lead are made from the same element (carbon).
—Guest Fact Man
vitamin-A
IT IS A TYPE OF ALCOHOL.(C20H29-OH). contains an ionone ring and hydrocarbon chain.
—Guest dhanashree
Lead Plumbing
The word "plumbing" comes from the word "plumbum", which is the old name for lead and the origin of its symbol Pb. Modern plumbing uses pipes made from PVC or copper rather than lead, which is highly toxic. However, you may find copper pipes with lead solder. Hard water tends to form mineral deposits which can protect against lead leaching into the water.
—Guest Anne
URL:http://chemistry.about.com/u/ua/chemistrydatabases/Chemistry-Facts-And-Trivia.01.htm
^CRIZAMICA BRONDIAL^
ReplyDeleteHere are some fun, interesting and sometimes weird chemistry facts.
Did you know... you can't taste food without saliva.
Did you know... it's possible to get sick or even die from drinking too much water.
Did you know... liquid oxygen is blue.
Did you know... fish scales are a common lipstick ingredient.
Did you know... some lipstick contains lead acetate or sugar of lead. This toxic lead compound makes the lipstick taste sweet.
Did you know... the average shot of espresso contains less caffeine than a typical cup of coffee.
Did you know... Coca Cola originally contained cocaine.
Did you know... lemons contain more sugar than strawberries, for the same mass.
Did you know... lobster blood is colorless until it is exposed to air. Then the blood appears blue.
Did you know... goldfish eyes perceive not only the visible spectrum, but also infrared and ultraviolet light.
Did you know... when you freeze saltwater or seawater slowly, you get freshwater ice. Icebergs are freshwater, too, although that is because they come from glaciers, which are made from freshwater (snow).
Did you know... if you exposed a glass of water to space, it would boil rather than freeze. However, the water vapor would crystallize into ice afterward.
Did you know... fresh egg will sink in fresh water. A stale egg will float.
Did you know... the wallpaper in Napoleon's room was dyed with Scheele’s Green, which contains copper arsenide. In 1893 the Italian biochemist Gosio found that dampening wallpaper containing Scheele’s Green allowed a mold to convert the copper arsenide into poisonous arsenic vapor. Although this may not have been the cause of Napoleon's death, it certainly can't have helped his health!
Did you know... sound travels 4.3 times faster in water than in air. Of course, it doesn't travel through a vacuum at all.
Did you know... about 78% of the average human brain consists of water.
Did you know... macadamia nuts are toxic dogs.
Did you know... a lightning strike can reach a temperature of 30,000 degrees Celsius or 54,000 degrees Fahrenheit.
Did you know... fire typically spreads uphills more quickly than downhill. This is because temperature affects the rate of combustion. The region above a fire tends to be much hotter than the area below it, plus it may have a better supply of fresh air.
Did you know... frogs don't need to drink water since they can absorb it through their skin. Humans, on the other hand, have waterproofing proteins in their skin to help prevent water loss.
Did you know... the hardest chemical in your body is your tooth enamel.
Did you know... urine fluoresces or glows under ultraviolet light.
Did you know... pearls, bones and teeth will dissolve in vinegar, which contains weak acetic acid.
Did you know... the chemical name for water is dihydrogen monoxde.
Did you know... you can extend the life of rubberbands by storing them in the refrigerator.
Did you know... the ethylene gas produced by a ripening apple ripens other apples as well as many other types of produce.
Did you know... water expands about 9% when it freezes into ice.
Did you know... Mars is red because its surface contains a lot of iron oxide or rust.
Did you know... you've lost about 1% of your body's water by the time you feel thirsty.
Did you know... you have chemoreceptors or taste buds on the inside of your cheek as well as on your tongue.
Did you know... it's possible for hot water to freeze more quickly than cold water.
URL:http://chemistry.about.com/od/weirdscience/a/Did-You-Know.htm
Chemistry Facts & Trivia
ReplyDeleteThe eight 'Noble metals' — ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold — do not rust.
Tabletop "volcanoes" can be created using 'Vesuvian Fire' compound Ammonium dichromate.
Just one atomic layer thick, the 'miracle material' Graphene is a better conductor of electricity and heat than any material.
Graphite can be transformed into diamond by applying a temperature of 3000°C and pressure of 100,000 atm.
Submitted by: Hyde - Toronto, Ontario, Canada
The coldest state of matter — Bose-Einstein Condensate superfluid — defies gravity and instead of flowing down, it flows upward.
The element Californium is often called the most expensive substance in the world (as much as $68 million for one gram.)
Aluminium is the most common metal in the Earth's crust (8 percent of its weight.)
Unlike any other element, helium does not solidify.
Hot water freezes faster than cold water (the Mpemba effect.)
Astatine is the rarest element on Earth (approx 28g in the Earth's entire crust.)
Source: http://www.sciensational.com/chemistry.html
that's all :)
trivia time:would you believe that freezing water can produce a violet explosion ? a cast iorn ball filled w/ water is placed in a beaker of dry ice & alcohol. as the water freezes & expards a huge anut.of force exerted against the wall of the cast iorn ball ,causing it to eventually explode
ReplyDelete-li8fe science library/water
*Trivia # 1:
What makes Chili peppers so hot?
>Some like it hot and if you’re one of them then you like capsaicin. It’s the chemical that makes your mouth burn when you eat chili peppers. Capsaicin causes this burning sensation in all mammals.
Plants produce capsaicin to protect their seeds from mammals that destroy their seeds when they eat the plant's fruit. When birds eat the fruit they don’t hurt the seeds, in fact they help the plant distribute them. So, it’s not a surprise that birds can’t sense capsaicin and aren’t bothered by it.
The seeds themselves don’t contain capsaicin. Instead its found in the “white” cross wall and veins of the pod and to a lesser extent the fleshy part.
The most scientific way to measure the hotness or piquancy of different chili peppers is to use high-performance liquid chromatography, but this method is more expensive than the older “Scoville” method. The Scoville method is more subjective and uses a group of taste testers (usually around 5) to rate the hotness.
Below is a chart showing the Scoville heat units for a variety of peppers
he eight 'Noble metals' — ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold — do not rust.
ReplyDeleteThe coldest state of matter — Bose-Einstein Condensate superfluid — defies gravity and instead of flowing down, it flows upward.
The noble gas Xenon lasers can cut through materials that are so tough even diamond tipped blades will not cut.
http://www.sciensational.com/chemistry.html
Chemical bonds link together atoms to make molecules (see molecules).
ReplyDeleteAtoms can bond in three main ways: ionic bonds, covalent bonds and metallic bonds.
In ionic bonds electrons are transferred between atoms.
Ionic bonds occur when atoms with just a few electrons in their outer shell give the electrons to atoms with just a few missing from their outer shell.
An atom that loses an electron becomes positively charged; an atom that gains an electron becomes negatively charged so the two atoms are drawn together by the electrical attraction of opposites.
Sodium loses an electron and chlorine gains one to form the ionic bond of sodium chloride (table salt) molecules.
In covalent bonding, the atoms in a molecule share electrons.
Because they are negatively charged, the shared electrons are drawn equally to the positive nucleus of both atoms involved. The atoms are held together by the attraction between each nucleus and the shared electrons.
In metallic bonds huge numbers of atoms lose their electrons. They are held together in a lattice by the attraction between ‘free’ electrons and positive nuclei.
Chemical Compound Facts
by admin on Saturday, July 17, 2010 3:04 under Interesting Facts.
Read full story
Compounds are substances that are made when the atoms of two or more different elements join together.
The properties of a compound are usually very different from those of the elements which it is made of.
Compounds are different from mixtures because the elements are joined together chemically. They can only be separated by a chemical reaction.
Every molecule of a compound is exactly the same combination of atoms.
The scientific name of a compound is usually a combination of the elements involved, although it might have a different common name.
Table salt is the chemical compound sodium chloride. Each molecule has one sodium and one chlorine atom.
The chemical formula of a compound summarizes which atoms a molecule is made of. The chemical formula for water is H 20 because each water molecule has two hydrogen (H) atoms and one oxygen (0) atom.
Table salt, or sodium chloride, forms when sodium Hydroxide neutralizes hydrocloric acid.
There only 100 or so elements but they can combine in different ways to form many millions of compounds.
The same combination of elements, such as carbon and hydrogen, can form many different compounds.
Compounds are either organic (see organic chemistry), which means they contain carbon atoms, or inorganic.
The eight 'Noble metals' — ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold — do not rust.
ReplyDeleteThe coldest state of matter — Bose-Einstein Condensate superfluid — defies gravity and instead of flowing down, it flows upward.Internal Links
U.S., Russian scientists find element 118Watch out, Superman! Kryptonite found on Earth
A new element is set to occupy spot 112 on the periodic table.(iStock)Scientists are about to add a new, super-heavy element to the periodic table.
"The new element is approximately 277 times heavier than hydrogen, making it the heaviest element in the periodic table," the German scientists who produced the element said in a statement on Wednesday.
The new element is massive and unstable — it can only exist for fractions of a second before splitting up in radioactive decay. It will occupy spot 112 on the periodic table. Elements are assigned numbers on the table based on how many protons they have.
The team of German researchers at the GSI Helmholtz Center for Heavy Ion Research produced the element for the first time a decade ago. The experiment that created it is very hard to duplicate, so it took years for the International Union of Pure and Applied Chemistry (IUPAC) to independently verify its existence.
The same team that produced element 112 is also responsible for adding elements 107-111 to the periodic table. Sigurd Hofmann, who led the team at the Centre for Heavy Ion Research, has been working on adding to the table since 1976.
Hofmann and his research team made element 112 by firing charged zinc atoms at lead atoms with a particle accelerator. The nuclei of the two atoms merged and immediately begin to decay. The researchers then calculated the size of the fused nucleus by measuring the amount of energy emitted by the decaying particle.
The team's next job is to propose a name for the element. This has to be done before it can be formally added to the periodic table.
Assigning Oxidation Numbers
ReplyDeleteOxidation-reduction reactions (redox reactions) are reactions in which electrons are lost by an atom or ion in one reactant and gained by an atom or ion in another reactant. Although electrons are gained and lost in these reactions, the balanced equation for a redox reaction does not show the electrons that are being transferred. In order to tell whether a redox reaction has occurred or not, we need a way to keep track of electrons. The best way to do so is by assigning oxidation numbers to the atoms or ions involved in a chemical reaction.
Oxidation numbers are hypothetical numbers assigned to an individual atom or ion present in a substance using a set of rules. Oxidation numbers (or oxidation states as they are also called) can be positive, negative, or zero. It is VERY IMPORTANT to remember that oxidation numbers are always reported for one individual atom or ion and not for groups of atoms or ions.
DUDE we just did a unit on this in my class! its pretty simple, just remember these rules:
the thing you MUST do FIRST is look for any H's, O's, or F's in the equation
1)any element just by itself not in a compound, their oxidation number is 0
ex: H2's oxidation number is 0
ex: Ag: oxidation number is 0 if its just something like Ag + BLA = LALA
2) the oxidation number of H is always +1, unless its just by itself (see #1)
3) the oxidation number of O is always -2, unless its just by itself (see #1)
4) the oxidation number of F is always -1, unless its just by itself (see#1)
ok so after you have written those oxidation numbers in rules 1-4 over each H, F, or O atom in the compound, you can look at the elements that we havent talked about yet
for example::::
N2O4
the oxidation number of O is -2.
since there are 4 O's, the charge is -8. now remember that N2O4 has to be neutral so the N2 must have a charge of +8
+8 divided by 2 = +4
N has an oxidation number of +4.
more rules:
5) the sum of oxidation numbers in a compound add up to 0 (when multiplied by the subscripts!!!) (see above example)
6) the sum of oxidation numbers in a polyatomic ion is the charge (for example, PO4 has a charge of (-3) so
oxidation # of O = -2. (there are 4 O's = -8 charge on that side ) P must have an oxidation number of 5. (-8+5= -3), and -3 is the total charge of the polyatomic ion.
THESE ARE VERY SIMPLE RULES THAT YOU HAVE TO REMEMBER. the stuff everyone else is talking about like the group 1 and etc, column 1 or 7, they're just talking about the charges. make sure that you don't listen to them, because other than H, F, and O, most of the elements in their compounds DO NOT have their charge as their oxidation number. in the first example N2O2, N's charge is -3 according to the periodic table, but in the example it turned out to be +4. CHARGES are misleading!
Very Cold!
ReplyDeleteThe lowest temperature reached in the laboratory is 7 nanokelvins, very near to absolute zero. The temperature was reached when helium was cooled to become a superfluid -- a fluid that could defy gravity.
Cops and Copper
Cops got the nickname because buttons on their uniforms use to be made of copper metal. In England, policemen were nicknamed "coppers" and the US has shortened this to "cops."
Graphite
Graphite can be transformed into diamond by applying a temperature of 3000°C and pressure of 100,000 atm
William Jefferson poh 2 sir!!
ginamit q poh kay MILLARD kc d aq naka register!!he eight 'Noble metals' — ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold — do not rust.
The coldest state of matter — Bose-Einstein Condensate superfluid — defies gravity and instead of flowing down, it flows upward.Internal Links
U.S., Russian scientists find element 118Watch out, Superman! Kryptonite found on Earth
A new element is set to occupy spot 112 on the periodic table.(iStock)Scientists are about to add a new, super-heavy element to the periodic table.
"The new element is approximately 277 times heavier than hydrogen, making it the heaviest element in the periodic table," the German scientists who produced the element said in a statement on Wednesday.
Have you ever unintentionally burnt a slice of bread in the toaster? The blackness you notice over the burnt bread is because of the traces of burnt carbon. Carbon exists in both mineral form (such as coal, diamond, carbon dioxide in das form or dissolved in water) and in organic form.
ReplyDeleteFOUR MAJOR SOURCES OF CARBON PRESENT ON EARTH
Atmosphere: Carbon dioxide
Hydrosphere: Carbon dioxide, bicarbonate
Lithosphere: Petroleum, coal, natural gas, carbon
Biosphere: Organic molecules within the organism
Most of the carbon in the nature is present in the form of carbon dioxide. The carbon from the carbon dioxide is very significant for photosynthesis. The carbon dioxide in air is used in the process of photosynthesis together with water and nutritional salts.
Organic carbon, which is the building block of living organisms, is generated through the process of photosynthesis from the carbon dioxide gas available in the atmosphere or dissolved in the sea water.
Here’s your daily dose of Chemistry related trivia… actually biochemistry trivia today. You hear the term carbohydrate all the time, but where did the term carbohydrate come from?
ReplyDeleteIn organic chemistry there are groups of certain atoms referred to as functional groups. These functional groups are usually attached to at least one carbon atom and help give a molecule it’s name. For example, -PO43- is called a phosphate. Hence the name of H12N3O4P, a common ingredient in fertilizer, is named ammonium phosphate.
What does all this have to do with carbohydrates? A common base formula for simple sugars is CH2O. Therefore early scientists simple called sugars carbohydrates due to the H2O attached to the carbon atom."The new element is approximately 277 times heavier than hydrogen, making it the heaviest element in the periodic table," the German scientists who produced the element said in a statement on Wednesday.
The new element is massive and unstable — it can only exist for fractions of a second before splitting up in radioactive decay. It will occupy spot 112 on the periodic table. Elements are assigned numbers on the table based on how many protons they have.
The team of German researchers at the GSI Helmholtz Center for Heavy Ion Research produced the element for the first time a decade ago. The experiment that created it is very hard to duplicate, so it took years for the International Union of Pure and Applied Chemistry (IUPAC) to independently verify its existence.
The same team that produced element 112 is also responsible for adding elements 107-111 to the periodic table. Sigurd Hofmann, who led the team at the Centre for Heavy Ion Research, has been working on adding to the table since 1976.
Hofmann and his research team made element 112 by firing charged zinc atoms at lead atoms with a particle accelerator. The nuclei of the two atoms merged and immediately begin to decay. The researchers then calculated the size of the fused nucleus by measuring the amount of energy emitted by the decaying particle.
FOUR MAJOR SOURCES OF CARBON PRESENT ON EARTH
ReplyDeleteAtmosphere: Carbon dioxide
Hydrosphere: Carbon dioxide, bicarbonate
Lithosphere: Petroleum, coal, natural gas, carbon
Biosphere: Organic molecules within the organism
Most of the carbon in the nature is present in the form of carbon dioxide. The carbon from the carbon dioxide is very significant for photosynthesis. The carbon dioxide in air is used in the process of photosynthesis together with water and nutritional salts.
Organic carbon, which is the building block of living organisms, is generated through the process of photosynthesis from the carbon dioxide gas available in the atmosphere or dissolved in the sea water.
Green plants, animal and vegetal parasites recycle carbon into carbon dioxide gas by decomposing organic matter. The residues, feces and corpses also decompose recycling the carbon dioxide present in their structure.
As seen in the figure, carbon dioxide that is present in the atmosphere in gas form and in the hydrosphere in dissolved form is the main source of carbon for living organisms. A part of the carbon within the animal body is recycled back into the atmosphere as CO2 through respiration in the mitochondrion.
Food + Oxygen --> Water + Carbon dioxide + Energy
(Mitochondrion)
The carbon in the remains and the wastes of all organisms is released back in the form of CO2 following a series of events such as putrefaction and decomposition – Fermentation.
Rub the petals of a red chinarose on a piece of white paper and let it dry for two minutes in air. Now just put a single drop of lemon sap on it, you will see a color change from blue to red. Here you have made a litmus paper- a quick and simple way to test the presence of acid and base.
ReplyDelete—Guest krishnendu
Atmosphere
Oxygen is not the most abundant element in our atmosphere. The most abundant element is Nitrogen, 78% while Oxygen is 21% and Argon is just short of 1%. Carbon Dioxide and trace elements make up the rest.
—Guest Matt
When the noble ones combine...
Xenon hexaflouroplatinate (XePtF6) is the first compound with a noble gas in it. It was first produced by Neil*Name three allotropes of Carbon
Question: Name three allotropes of Carbon: Answer: Diamond, Graphite, and Fullerene...
*Tungsten(W)
Tungsten has highest m.p(3300centigrate).so it is used as a filament in bulb.
*mnemonic for organics
Most Electrons Prefer Bonding=MEPB= Methane Ethane Propane Butane
*litmus
Rub the petals of a red chinarose on a piece of white paper and let it dry for two minutes in air. Now just put a single drop of lemon sap on it, you will see a color change from blue to red. Here you have made a litmus paper- a quick and simple way to test the presence of acid and base.
*Atmosphere
Oxygen is not the most abundant element in our atmosphere. The most abundant element is Nitrogen, 78% while Oxygen is 21% and Argon is just short of 1%. Carbon Dioxide and trace elements make up the rest.
*When the noble ones combine...
Xenon hexaflouroplatinate (XePtF6) is the first compound with a noble gas in it. It was first produced by Neil Bartlett in 1962.
*Fastest Half-Life
Berrylium-8 has the shortest half-life, 70 x 10^-18 seconds, or 0.000000000000000070 seconds.
*Very Cold!
The lowest temperature reached in the laboratory is 7 nanokelvins, very near to absolute zero. The temperature was reached when helium was cooled to become a superfluid -- a fluid that could defy gravity.
*Cops and Copper
Cops got the nickname because buttons on their uniforms use to be made of copper metal. In England, policemen were nicknamed "coppers" and the US has shortened this to "cops."
*Giant Molecules
Rubber like you see on wheels of vehicles is actually one giant molecule.
*diamond
a diamond does not melt in acid.the only thing that can melt is the intense heat.
*PRABHAT (P+A)
red phosphorus is a non-metal. it is not malleable and forms acidic oxide.
URL:http://chemistry.about.com/u/ua/chemistrydatabases/Chemistry-Facts-And-Trivia.htm Bartlett in 1962.
This comment has been removed by the author.
ReplyDelete...............................PATRICK BURCE .......................................... TRIVIA:
ReplyDeleteAntoine Jerome Balard Balard was a French chemist who who isolated and identified the element bromine. He was conducting a general investigation of seawater when he found the previously unknown element in seaweed and several marine animals.
Carl Wilhelm Scheele
Scheele was a German-Swedish apothecary who independently discovered oxygen. Joseph Priestly is also credited with this discovery since be published his findings first. He also discovered barium, manganese, molybdenum, tungsten and chlorine.
Georg Ernst Stahl
Stahl was a German chemist and physician best remembered for his phlogiston theory of combustion. According to the theory, all flammable objects carry phlogiston that is released when the object burns. When the body runs out of phlogiston, the fire goes out. When metals release their phlogiston, they rust. This theory was widely accepted for nearly a century and was one of the bridges between alchemy and chemistry.
Karl Klaus
Klaus was a Russian chemist who discovered the element ruthenium. He was researching platinum metals or osmium, palladium, iridium and rhodium and found ruthenium in the waste material from a platinum refinery.
Friedrich Wilhelm Georg Kohlrausch
Kohlrausch was a German physical chemist who focused on the thermal, electrical and magnetic properties of electrolytes. Electrolytes are substances that conduct electricity in solutions through the transfer of ions. He was the first to demonstrate electrolytes have a constant electrical resistance and measured the velocities of the transferred ions for a particular electrolyte.
url: http://chemistry.about.com/lr/famous_chemists/518694/1/
~ALYSSA MAE BONCALOS III-7~
ReplyDelete*Neptunium was named after the planet Neptune which was in turn named after the Greek god.
Element 93, Neptunium, was originally named bohemium, ausonium, and sequanium by three separate “discoverers” of Neptunium. Only problem is, they never actually discovered the element. The element wasn’t truly discovered until 1940 at which point it was proven to exist and was named.
The name Neptunium was originally considered for the element named after the country of Germany, Germanium.
Chemistry out connection to the world around us.Chemistry is a broad field called CENTRAL SCIENCE because it touches nearly every aspect of human life.In chemistry we will learn more about science,technology and importance of the nature of chemistry as well as the process of science.
ReplyDeleteCan you imagine counting the number of molecules in a raindrop or number of atoms in a small piece of charcoal?it may seem impossible for anyone to do it since we know that these particles are so tiny and invisible to the naked eye.It is impractical to try counting these things which you can neither see or feel but scientist have a way of doing this.They were able to count the number of atoms in an element or the number of molecules in a compound this measured quantity corresponds to avogadro's number.
An ordinary person may define science as a body of information.Philosophers regard it as way of questioning the truthfulness of knowledge.Scientist may view it as a search for facts about the world around us and finding logical explanations for what they observe
Chemistry Capacity
ReplyDeleteLast grading, I’ve learned about the Importance of Periodic Table in our lives. This grading we tackled about the Electron Sharing between Non-metal which includes the Lewis Dot Structure, the covalent bond and non-covalent bond. The Bonding between Atoms which indicates the chemical equation. The difference betweenIntramolecular and Intermolecular. We tackled also the difference of physical and chemical changes in every substance which indicated the exothermic and endothermic. The Types of Chemical Reactions in each Chemical Equations.I’ve learned the Oxidizing and Reducing Agent on a substance if when and where they occur. The Energy changes in Chemical Reactions , which involves the Exothermic and Endothermic and the difference between the Spontaneous and Non-spontaneous process.
First the Bonding Between Atoms which indicates the chemical equations which mean the attractive force existing between any two atoms. The Difference between Intramolecular and Intermolecular forces, Intramolecular are the chemical bonds that are formed or broken when a substance participates in a chemical reaction and the Intermolecular which exists between molecules and it cannot define the existence of the three phases of matter , particularly the solid and the liquid phrases. I’ve learned about the Electron Sharing between Non-metals which includes the covalent bond,
which the sharing of electrons binds the combined atoms together. Lewis dot structure is represented by the symbol of the element surrounded by the valence electrons represented by dots. The physical changes which involves changes in physical properties such as size, shape and density or changes in phase without undergoing a change in the composition of the substance. The Chemical Changes , undergoes change in its composition and or structure and there a new substance are formed that has different properties and composition from the original material. My favorite lesson which is the Types of Chemical Reactions which is the Decomposition define as when a single reactant breaks down into several products , with the formula of AB A + B. Combination involves several reactants combining to form a single product , with the formula unit of A + B AB. Single Displacement , this occurs when an active substance replaces another element from its compound , with the formula of A + BC AC + B.
Double Displacement which two substances exchange atoms or groups of atoms (or what we called polyatomic ions) in type of reaction , with the formula unit of AB + CD AD + CB. The Difference between Oxidation and Reduction , Oxidation is a reaction which usually involves direct combination with oxygen and involves increase in oxidation numberwhile the Reduction usually involves direct combines with hydrogen and involves a decrease in oxidation number. Their agents which are the Oxidizing Agent is the substance that is Reduced. The Reducing Agent is the substance which is Oxidized. Oxidation Reaction involves a loss of electrons during a complete transfer of electrons or a shift of shared electrons. A Reduction Reactions which involves gain of electrons during complete transfer of electrons of shift of shared electrons. The Energy Changes in Chemical Reactions which involves the Exothermic and Endothermic process. Exothermic process is the process which releases heat into the surroundings from the system and its Exothermic Reactions is Energy lost by system = Energy gained by surroundings. Endothermic process is the process which absorbs heat from the surroundings to the system and its Energy gained by the system = Energy lost by the surroundings. I’ve learned also the Spontaneous processes occur on its own, without any external driving force. Non-spontaneous processes cannot occur on their own and only takes place by some applied means.
It is very important to know this different processes and also the reaction because without it wedidn’t know how and why they occur. Without this study we will always be ignorant or unaware of all of those things in our surroundings. I am fulfilled with all of my learning here in Chemistry subject. It is so enjoyable to learn all of those lessons.
ReplyDelete:)
THE GENERAL PROPERTIES OF GASES
ReplyDelete*MOST GASES EXIST AS MOLECULES,USUALLY diatomic.EXAMPLES of these gases are oxygen(O2),iodine(I2),clorine(Cl2),and hydrogen (H2).however,noble gases, such as neon(Ne),argon(Ar),and helium (He) exist as individual atoms.They are called monatomic gases.
* gases have no definite shape and volume.They followthe shape of their cointainers and occupy all the space available.The volume of their container also becomes theirvolume.
* Gases are easily compressed when pressure is applied.
* Gases expand when heated and contract when cooled.
* Gases exert pressure.
MEASURABLE PROPERTIES OF GASES
ReplyDelete1.PRESSURE
=PRESSURE is defined as force per unit area.The pressure of a gas is the force exerted by the gases on the walls of its container divided by the surface area of the container.mathematically,pressure is expressed as pressure=force over area.
2.VOLUME
=The volume of gas is the space it occupies.Also,the volume of a vessel is equal to the gas it contains. This is based on the principle that gas particles occupies all the space available.The volume occupied by the gas molecules is negligible to the volume of its conitaner.
3.TEMPERATURE
=The temperature of a gas is determined using in a thermometer.it is usually expressed in three units,the degree celsius(0C),degree fahrenheit(0F),kelvin(K).
4.DENSITY
=Although gases are very light,they still have measurable densities.The densities of gases are very small compared with those of solid liquids .The density of a gases is computed by dividing the mass of the gas by its volume.
these fourth grading period we tackle about the different conversion unit like mole to mass conversation,The molar volume ,volume to mole ,mole to mole and mole to mass conversation The molar volume in volume to mole conversation is always in (STP)or standard temp,pressure.WE also discuss about limiting reactant reagent and excess reactant or reagent.ITS from the greek words "stoichion"means element emetron means measure.percentage composition is an expression for the ratio of the mass of a single element compound to the mass of a given compound containing the elements,all times 100.
ReplyDeleteWe also discuss The types of chemical formula, the empirical formula and the molecular formula.The impirical formula is the simplest formula and the molecular formula shows the exact number of atoms of each element in the smallest unit of a subtance.
ReplyDeleteKinetic-Molecular Theory
The ideal gas equation
pV = nRT
Has been presented as a compliation of empirical observation, i.e. the historically significant Gas Laws, but does The Ideal Gas equation have some deeper, more fundamental meaning?
The Kinetic-Molecular Theory ("the theory of moving molecules"; Rudolf Clausius, 1857)
Gases consist of large numbers of molecules (or atoms, in the case of the noble gases) that are in continuous, random motion. Usually there is a great distance between each other, so the molecules travel in straight lines between abrupt collisions at the walls and between each other. These collisions randomize the motion of the molecules. Most of the collisions between molecules are binary, in that only two molecules are involved.
The volume of the molecules of the gas is negligible compared to the total volume in which the gas is contained. A common bond length between atoms is about 10-10 m or 1 Angstrom. Small molecules are therefore on the order of 10 Angstroms in diameter, or less than 10-24 Liters in Molecular Volume, quite tiny indeed! Remember, however that there can be a great many molecules in the sample of gas, perhaps on the order of a mole, or 6 x 1023. So that when concentrations of molecules exceed about 1 mol/liter, then the approximation that the volume of ALL the molecules in the container is much less than the volume of the container itself, fails. In the case of an ideal gas, we will assume that molecules are point masses, i.e., the volume of a mole of gas molecules (as if they were at rest) is zero, so molecular and container volumes never become comparable.
Attractive forces between gas molecules are negligible. We know that if these forces were significant, the molecules would stick together. This happens when it rains and gaseous water molecules stick together to form a liquid. Water vapor is a condensible gas, and this shows us that gas molecules are sticky, but at a high enough temperature they form only a permanent gas, because their stickiness can be considered negligible. We will assume that in an ideal gas, molecular attractive forces are not just small, but identically zero.
Consequences:
The average kinetic energy of the molecules does not change with time. The molecules bounce and bounce but, on average, do not slow down as long as the temperature of the gas remains constant. Energy can be transferred between molecules during collisions but not lost because the collisions are perfectly elastic (not sticky)
The average kinetic energy of the molecules is proportional to absolute temperature (A result of Thermodynamics). At a given temperature the molecules of all species of gas, no matter what size shape or weight, have the same average kinetic energy.
Gas Laws and Kinetic Theory
ReplyDeleteAt constant temperature, the average kinetic energy of the gas molecules remains constant
Therefore, the rms speed of the molecules, u, also remains unchanged
If the rms speed remains unchanged, but the volume increases, there will be fewer collisions with the container walls over a a given time: Therefore, the pressure will decrease (Boyle's law)
An increase in temperature means an increase in the average kinetic energy of the gas molecules, thus an increase in u
At constant volume, the greater speed will mean more collisions per unit time and an increase in pressure
If, instead, we allow the volume to change to maintain constant pressure, the volume must increase with increasing temperature to maintain constant pressure (i.e. the number and strength of 'hits' per wall), which is just Charles's law
The Ideal Gas Equation of State follows directly from the Kinetic Theory of Gases. Here is a Pseudo-Derivation
Molecular Effusion and Diffusion
Kinetic-molecular theory states that the average kinetic energy of a mole of molecules molecules is proportional to absolute temperature, and the proportionality constant is R, the universal gas constant
(1/2)Mu2 = (3/2)R T = Molar Kinetic (translational) Energy of the gas
At a given temperature, all gases have the same average kinetic energy and for a three dimensional gas this value is (3/2)RT. (what is the molar kinetic energy of a two dimesional gas trapped in the surface of a metal?)
The rms velocity, u, in m/s, is simply
where M is the molar mass in kg/mole, R is the gas constant in J/K.mole, and T is the absolute temperature in K.
Numerical Example:
Calculate the rms speed, u, of an N2 molecule at room temperature (25°C) Be careful of your UNITS!
T = (25+273)K = 298K
M = 28 g/mol = 0.028 kg/mol
R = 8.314 J/mol K = 8.314 kg m2/s2 mol K
u = 515 m/s
Note: this is equal to 1,150 miles/hour!
Effusion
The escape of a gas through a tiny pore or pinhole in its container is called EFFUSION.
The effusion rate, r, has been found to be inversely proportional to the square root of its molar mass: (Why?)
Thus, comparison of the effusion rates of two gases with different masses will follow the relation:
This effect was observed in the 19th century by Graham and is sometimes called GRAHAM's LAW
A note on Rates and Times
The effusion time (the time it takes for a certain amount of gas to escape a vessel) is inversely proportional to the effusion rate (the amount of gas effusing from the hole per unit time). Be careful that you understand whether it is a rate or a time that you are calculating.
Gas may effuse, but for this to happen a molecule must pass through a pore or pinhole and escape to the outside. In effect, a molecule must 'collide' with an escape hole. The number of such collisions will be linearly proportional to the average speed of the molecules in the gas and thus the effusion rate. The effusion time should be inversely proportional to the average speed of the molecules or proportional to the square root of the ratio of the molecular masses..
The ratio of effusion rates, ri, for two gases labelled by i, is proportional to the ratio of the RMS speeds of the gases, ui
Diffusion
ReplyDeleteSimilarly to effusion, the process of diffusion is the spontaneous intermingling (mixing) of dissimilar gases (fluids) that are initially spatially separated. If you put a drop of ink in a glass of water and you see the ink gradually spread out to fill the glass, this is diffusion
The relative rates of diffusion of two gases is also determined by the ratio of their average (rms) speeds
The speed of molecules is quite high, but the rates of diffusion are slower than molecular speeds due to molecular collisions
At the density of the atmosphere at sea level, each gas molecule experiences collisions at a rate of about 1010 (i.e. 10 billion) times per second
Due to these collisions, the direction of a molecule of gas in the atmosphere is constantly changing, and the diffusion rate is much reduced from the instantaneous speed of the molecule
The average distance traveled by a molecule between collisions with another molecule is called the mean free path
The higher the density of gas, the smaller the mean free path (more likelyhood of a collision). The larger the molecules, the smaller the mean free path. The mean free path depends on the number density of the gas molecules and their size --- and nothing else
At sea level the mean free path of atmospheric gases is about 60 nm
At 100 km altitude, the atmosphere is less dense than where we live at the surface of the earth, and the mean free path is about 0.1 m (about 1 million times longer than at sea level)An increase in temperature means an increase in the average kinetic energy of the gas molecules, thus an increase in u
At constant volume, the greater speed will mean more collisions per unit time and an increase in pressure
If, instead, we allow the volume to change to maintain constant pressure, the volume must increase with increasing temperature to maintain constant pressure (i.e. the number and strength of 'hits' per wall), which is just Charles's law
The Ideal Gas Equation of State follows directly from the Kinetic Theory of Gases. Here is a Pseudo-Derivation
Molecular Effusion and Diffusion
Kinetic-molecular theory states that the average kinetic energy of a mole of molecules molecules is proportional to absolute temperature, and the proportionality constant is R, the universal gas constant.
Kinetic Molecular Theory of Gases
ReplyDelete�Before You Begin:
To master this material, you must know the gas laws.
A law is a summary of observations, and a theory is an explanation of those observations. The individual gas laws give us a set of mathematical tools to help predict the behavior of gases under specific conditions of pressure, temperature, volume and number of moles of gas. They do not, however, explain why gases behave the way they do. Kinetic molecular theory is an attempt to explain some of the bulk properties of matter by describing how particles interact with one another. Kinetic molecular theory can help us understand how and why the gas laws work and to predict when the gas laws won’t work.
Daniel Bernoulli started kinetic molecular theory in 1738 when he proposed a thought model consistent with Boyle’s Law in an attempt to explain how gases exert pressure. Clausius refined the theory in the mid-1800s.
The Assumptions of Kinetic Molecular Theory:
In order to explain how gases behave we can make the following assumptions:
A gas is composed of particles in constant motion.
The average kinetic energy depends on temperature, the higher the temperature, the higher the kinetic energy and the faster the particles are moving.
Compared to the space through which they travel, the particles that make up the gas are so small that their volume can be ignored.
The individual particles are neither attracted to one another nor do they repel one another.
When particles collide with one another (or the walls of the container) they bounce rather than stick. These collisions are elastic; if one particle gains kinetic energy another loses kinetic energy so that the average remains constant.
The KMT Assumptions and the Gas Law Variables:
We can connect these assumptions with the four variables from the individual gas laws.
Pressure is force per unit area. What we observe as the pressure of a gas is the force of collisions as the particles strike the walls of the container. If these collisions occur frequently, the gas pressure is high. If the collisions don’t occur very often, the pressure is low. Any change in the conditions that results in more frequent collisions will increase the pressure.
What we observe as the volume of a gas is the empty space the particles travel through. The larger the volume, the greater the distance between particles. Any change in the conditions that results in a longer distance between particles is due to an increase in volume.
What we observe as n, or number of moles, is the number of particles.
What we observe as temperature of a gas is the average speed of the particles. The hotter the gas, the faster the particles are moving. The speeds of the individual gas particles vary, but they form a statistical distribution of speeds that looks like the following graph:
hese fourth grading period we tackle about the different conversion unit like mole to mass conversation,The molar volume ,volume to mole ,mole to mole and mole to mass conversation The molar volume in volume to mole conversation is always in (STP)or standard temp,pressure.WE also discuss about limiting reactant reagent and excess reactant or reagent.ITS from the greek words "stoichion"means element emetron means measure.percentage composition is an expression for the ratio of the mass of a single element compound to the mass of a given compound containing the elements,all times 100.
ReplyDeleteGas Laws
Boyle's Law
Concepts
Boyle's Experiment
Some of the earliest quantitative measurements were performed on gases. One early study was conducted by Robert Boyle in 1662.
Robert Boyle employed a J-shaped piece of glass tubing that was sealed on one end. A gas (air) was trapped in the sealed end of the tube and varying amounts of mercury were added to the J-shaped tube to vary the pressure of the system. Boyle systematically varied the pressure and measured the volume of the gas. These measurements were performed using a fixed amount of gas and a constant temperature. In this way Boyle was able to examine the pressure-volume relationship without complications from other factors such as changes in temperature or amount of gas.
The manometer that was employed in the previous experiment can also be used to perform Boyle's experiment. A small amount of air is trapped in the sealed end of the manometer. The scale that is used to read the height of a column of mercury can also be used to read the height of the column of air. (You will need to estimate the position of the top of the tube, which is curved.) The inside diameter of the tube, 4.286 cm, and the height of the column of air can be used to calculated the volume of air.
The pressure of the gas will be varied in exactly the same manner as Robert Boyle varied the pressure: mercury will be added or removed from the open end of the manometer. After changing the pressure (by changing the amount of mercury in the manometer), the pressure and volume are recorded.
Data Analysis
Once the volume-pressure data has been obtained, the next challenge is to determine the mathematical relationship between the two properties. Although an enormous number of relationships are possible, one likely possibility is that the volume will be directly related to the pressure raised to some power:
V = CBL P a
The exponent a is expected to be independent of the mass of gas and temperature; the goal is to determine the value of a from the "experimental" data. The constant CBL is expected to vary with the mass of gas and the temperature; at this point, this constant is not of interest.
A simple way to determine the value of a is to prepare a plot of ln V vs ln P. If the proposed relationship is valid (and it might not be valid), this plot should yield a straight line of slope a. Thus the linearity of the plot serves as a test of our original hypothesis (that the volume-pressure relation may be described by the equation shown above).
marydiana bollosa iii-7
ReplyDeletefor the 4th grading period i had learned more about gases-Gas Properties,Kinetic Molecular Theory(KMT) & Gas Laws-Boyles Lawis ,Charles Law from Jacques Charles where @ constant pressure is directly proportional to its temp. & it is always express in Kelvin. Avogadros Law-states that equal gases @ the same temp. & pressure contain equal no. of molecules, Gay-lussacs Law, or the pressure law, was found by Joseph Louis Gay-Lussac in 1809. It states that the pressure exerted on a container's sides by an ideal gas is proportional to its temperature, Combined Gas Law are the combination of Charles,Boyles,&Gay-Lussaca Law,Ideal Gas Law
where
P is pressure
V is volume
n is the number of moles
R is the universal gas constant
T is temperature (K)
Jay-Ar Pacheco iii-7
ReplyDeleteFor the 4th grading in Chemistry i had learned about Stoichiometry is a branch of chemistry that deals with the relative quantities of reactants and products in chemical reactions. In a balanced chemical reaction, the relations among quantities of reactants and products typically form a ratio of positive integers.Limiting & Excess Reactant. Characteristic Properties of Gas:
Gas assumes the volume and shape of its container
Gas is very compressible
Gas has low density, compared to liquid and solid
Gas molecules have very free motion
Gas Laws
As the pressure of a gas increases, the volume decreases (the temperature is constant)
As the temperature of an enclosed gas increases, the volume increases (the pressure is constant)
As the temperature of an enclosed gas increases, the pressure increases (the volume is constant)
For the 4th grading in Chemistry i had learned about Stoichiometry is a branch of chemistry that deals with the relative quantities of reactants and products in chemical reactions. In a balanced chemical reaction, the relations among quantities of reactants and products typically form a ratio of positive integers.Limiting & Excess Reactant. Characteristic Properties of Gas:
ReplyDeleteChemical Formulas
Chemical Formulas
Chemical formulas such as HClO4 can be divided into empirical formula, molecular formula, and structural formula. Chemical symbols of elements in the chemical formula represent the elements present, and subscript numbers represent mole proportions of the proceeding elements. Note that no subscript number means a subscript of 1.
From a chemical point of view, an element contained in the substance is a fundamental question, and we represent the elemental composition by a chemical formula, such as H2O for water. This formula implies that the water molecules consist of 2 hydrogen, and 1 oxygen atoms. The formula H2O is also the molecular formula of water. For non-molecular substances such as table salt, we represent the composition with an empirical formula. Sodium chloride is represented by NaCl, meaning that sodium and chlorine ratio in sodium chloride is 1 to 1. Again, the subscript 1 is omitted. Since table salt is an ionic compound, the formula implies that numbers of Na+ ions, and Cl- ions are the same in the solid. The subscript numbers in an empirical formula should have no common divisor.
H H
| |
H-C-C-O-H
| |
H H
Structural of
CH3CH2OH
A 3-Dimensional
structure of C6H12
A structural formula reflects the bonding of atoms in a molecule or ion. For example, ethanol can be represented by CH3CH2OH. This is a simple way of representing a more elaborated structure shown on your left. Molecular structures are often beautiful, but the representation is an artwork. For example, a 3-dimensional structure of cyclohexane is shown on the right. This is a chair form, and another structure has a boat form. You will learn more about it in organic chemistry. The molecular formula of benzene is C6H6, and its empirical formula is CH.
You may refer to a substance by its name, and recognize it by its properties. Properties are related to the structure and the composition of the molecules. Knowing the chemical formula is a giant step towards understanding a substance.
Formula Weights, Molecular Weights and Molar Masses
The formula weight is the sum of all the atomic weights in a formula. The evaluation of formula weight is illustrated in this example.
Example 1
What is the formula weight of sufuric acid H2SO4?
Solution:
The formula also indicates a mass as the sum of masses calculate this way
2*1.008 + 32.0 + 4*16.0 = 98.0
where 1.008, 32.0 and 16.0 are the atomic weights of H, S, and O respectively.
Discussion:
If the formula is a molecular formula, the mass associated with it is called molecular mass or molecular weight. As an exercise, work out the following problem.
What is the molecular weight of caffeine, C8H10N4O2?
The diagram shown here is a model of the caffeine molecule.
With the aid of a table of atomic weights, a formula indirectly represents the formula weight. If the formula is a molecular formula, it indirectly represents the molecular weight. For simplicity, we may call these weights molar masses, which can be formula weights or molecular weights.
A chemical formula not only represents what a substance is made of, it provides a great deal of information about the substance. Do you know that chemical formulas are used all over the world, regardless of the language? Chinese, Russian, Japanese, African, and South Americans use the same notations we do. Thus, H2S is recognized as a smelly gas all over the world. Chemical formula is an international or universal language.
The combined gas law is a gas law which combines Charles's law, Boyle's law, and Gay-Lussac's law. There is no official founder for this law; it is merely an amalgamation of the three previously discovered laws. These laws each relate one thermodynamic variable to another mathematically while holding everything else constant. Charles's law states that volume and temperature are directly proportional to each other as long as pressure is held constant. Boyle's law asserts that pressure and volume are inversely proportional to each other at fixed temperature. Finally, Gay-Lussac's law introduces a direct proportionality between temperature and pressure as long as it is at a constant volume. The inter-dependence of these variables is shown in the combined gas law, which clearly states that:
ReplyDelete“ The ratio between the pressure-volume product and the temperature of a system remains constant. ”
This can be stated mathematically as
where:
p is the pressure
V is the volume
T is the temperature measured in kelvins
k is a constant (with units of energy divided by temperature).
For comparing the same substance under two different sets of conditions, the law can be written as:
The addition of Avogadro's law to the combined gas law yields the ideal gas law.
Contents [hide]
1 Derivation from the Gas Laws
2 Physical Derivation
3 Applications
4 See also
5 Notes
6 Sources
7 External links
[edit]Derivation from the Gas Laws
Main article: Gas Laws
Boyle's Law states that the pressure-volume product is constant:
Charles's Law shows that the volume is proportional to absolute temperature:
Gay-Lussac's Law says that the pressure is proportional to the absolute temperature:
where P is the pressure, V the volume and T the absolute temperature and of an ideal gas.
By combining (1) and either of (2) or (3) we can gain a new equation with P, V and T. Equation (2) is used in this example, and the arbitrary subscript on the constant is dropped so that k = k2.
Gas Laws
ReplyDeleteBoyle's Law
Concepts
Boyle's Experiment
Some of the earliest quantitative measurements were performed on gases. One early study was conducted by Robert Boyle in 1662.
Robert Boyle employed a J-shaped piece of glass tubing that was sealed on one end. A gas (air) was trapped in the sealed end of the tube and varying amounts of mercury were added to the J-shaped tube to vary the pressure of the system. Boyle systematically varied the pressure and measured the volume of the gas. These measurements were performed using a fixed amount of gas and a constant temperature. In this way Boyle was able to examine the pressure-volume relationship without complications from other factors such as changes in temperature or amount of gas.
The manometer that was employed in the previous experiment can also be used to perform Boyle's experiment. A small amount of air is trapped in the sealed end of the manometer. The scale that is used to read the height of a column of mercury can also be used to read the height of the column of air. (You will need to estimate the position of the top of the tube, which is curved.) The inside diameter of the tube, 4.286 cm, and the height of the column of air can be used to calculated the volume of air.
The pressure of the gas will be varied in exactly the same manner as Robert Boyle varied the pressure: mercury will be added or removed from the open end of the manometer. After changing the pressure (by changing the amount of mercury in the manometer), the pressure and volume are recorded.
Data Analysis
Once the volume-pressure data has been obtained, the next challenge is to determine the mathematical relationship between the two properties. Although an enormous number of relationships are possible, one likely possibility is that the volume will be directly related to the pressure raised to some power:
V = CBL P a
The exponent a is expected to be independent of the mass of gas and temperature; the goal is to determine the value of a from the "experimental" data. The constant CBL is expected to vary with the mass of gas and the temperature; at this point, this constant is not of interest.
A simple way to determine the value of a is to prepare a plot of ln V vs ln P. If the proposed relationship is valid (and it might not be valid), this plot should yield a straight line of slope a. Thus the linearity of the plot serves as a test of our original hypothesis (that the volume-pressure relation may be described by the equation shown above).
Experiment
Objective
Determine how the volume of a gas changes with the pressure for a fixed amount of gas and temperature.
Part 1
The basic details of the experiment have been described above. The open tube of the manometer is exposed to the atmosphere. Consequently the atmospheric pressure (Patm) must be added to the pressure exerted by the column of mercury.
The first step in the experiment is thus to measure the atmospheric pressure using the manometer containing no trapped air.
Part 2
A sample of air is now trapped in the closed end of the manometer.
Carefully measure the heights of the columns of mercury and the column of trapped air. (The trapped air has artificially been given a light green color.) Use this data to calculate the volume of the trapped gas and the pressure. The inside diameter of the manometer tube is 4.286 cm. You will need to use the value for Patm measured in Part 1 of this experiment.
Change the amount of mercury in the manometer and once again measure the volume and pressure. Continue this process until data is obtained for at least five different pressures.
Notice that sometimes the column of mercury on the left is higher than that on the right and sometimes the reverse is true. Why does this occur? Make sure you take this effect into account in calculating the pressure.
For each pair of volume-pressure values, enter the data in the table. The point will automatically be plotted on the graph.
Carefully examine the plots of V vs P and ln V vs ln P and determine the value of a.
CHEMICAL BONDING
ReplyDelete> atoms combine to become stable
> noble gases have already stable atoms
> metallic elements become cation during chemical reaction
> non-metallic elements become anion during chemical reaction
Chemical Bonding / intract molecular forms
- attraction between two substances
- involves intercation of electrons
- attractive force holding the electron in a molecule or ions
A chemical bond is the result of an attraction between atoms or ions. The types of bonds that a molecule contains will determine its physical properties, such as melting point, hardness, electrical and thermal conductivity, and solubility. How do chemical bonds occur? As we mentioned before, only the outermost, or valence, electrons of an atom are involved in chemical bonds. Let’s begin our discussion by looking at the simplest element, hydrogen. When two hydrogen atoms approach each other, electron-electron repulsion and proton-proton repulsion both act to try to keep the atoms apart. However, proton-electron attraction can counterbalance this, pulling the two hydrogen atoms together so that a bond is formed. Look at the energy diagram below for the formation of an H–H bond.
As you’ll see throughout our discussion, atoms will often gain, lose, or share electrons in order to possess the same number of electrons as the noble gas that’s nearest them on the periodic table. All of the noble gases have eight valence electrons (s2p6) and are very chemically stable, so this phenomenon is known as the octet rule. There are, however, certain exceptions to the octet rule. One group of exceptions is atoms with fewer than eight electrons—hydrogen (H) has just one electron. In BeH2, there are only four valence electrons around Be: Beryllium contributes two electrons and each hydrogen contributes one. The second exception to the octet rule is seen in elements in periods 4 and higher. Atoms of these elements can be surrounded by more than four valence pairs in certain compounds.
IONIC AND COVALENT BOND
ReplyDeleteThere are many types of chemical bonds and forces to bind molecules together. Two most basic types of bonds characterized as either ionic or covalent.
Ionic bond
- electrostatic attraction between 2 oppositely charge particles ( there is a metal & nonmetals )
- involves transfer from metal to nonmetal
- require at least one electron donor and one electron accepter
Covalent bond
- involves sharing of electrons ( 2 or more nonmetals )
- atoms that have the same electronegativity share electrons in covalent bonds since donating or receiving electrons is unfavorable.
Ionic Bonding: Ionic bonding is the complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates 2 oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the non-metal accepts those electrons to become a negatively charged anion. Ionic bonds require an electron donor, metal, and an electron accepter, nonmetal.
ReplyDeleteIonic Bonding is observed because metals have few electrons in its outer-most orbital. By losing those electrons, these metals can achieve noble-gas configuration and satisfy the octet rule. Similarly, nonmetals that have close to 8 electrons in its valence shell tend to readily accept electrons to achieve its noble gas configuration. In ionic bonding, more than 1 electron can be donated or received to satisfy the octet rule. The charge on the anion and cation corresponds to the number of electrons donated or recieved. In ionic bonds, the net charge of the compound must be zero.
This sodium molecule donates the lone electron in its valence orbital in order to achieve octet configuration. This creates a positively charged cation due to the loss of electron.
This Chlorine molecule receives one electron to achieve its octet configuration. This creates a negatively charged anion due to the addition of one electron.
The predicted overall energy of the ionic bonding process, which includes the ionization energy of the metal and electron affinity of the nonmetal, is usually positive, indicating that the reaction is endothermic and unfavorable. However, this reaction is highly favorable because of their electrostatic attraction. At the most ideal inter-atomic distance, attraction between these particles releases enough energy to facilitate the reaction. Most ionic compounds tend to dissociate in polar solvents because they are often polar. This phenomenon is due to the opposite charges on each ions.
Examples:
In this example, the Sodium molecule is donating its 1 valence electron to the Chlorine molecule. This creates a Sodium cation and a Chlorine anion. Notice that the net charge of the compound is 0.
In this example, the Magnesium molecule is donating both of its valence electrons to Chlorine molecules. Each Chlorine molecule can only accept 1 electron before it can achieve its noble gas configuration; therefore, 2 molecules of Chlorine is required to accept the 2 electrons donated by the Magnesium. Notice that the net charge of the compound is 0.
Covalent Bonding: Covalent bonding is the sharing of electrons between atoms. This type of bonding occurs between two of the same element or elements close to each other in the periodic table. This bonding occurs primarily between nonmetals; however, it can also be observed between nonmetals and metals as well.
When molecules have similar electronegativity, same affinity for electrons, covalent bonds are most likely to occur. Since both atoms have the same affinity for electrons and neither is willing to donate them, they share electrons in order to achieve octet configuration and become more stable. In addition, the ionization energy of the atom is too large and the electron affinity of the atom is too small for ionic bonding to occur. For example: Carbon doesnt form ionic bonds since it has 4 valence electrons, half of an octet. In order to form ionic bonds, Carbon molecules must either gain or lose 4 electrons. This is highly unfavorable; therefore, Carbon molecules share their 4 valence electrons through single, double, and triple bonds so that each atom can achieve noble gas configurations. Covalent bonds can include interactions of the sigma and pi orbitals; therefore covalent bonds lead to formation of single, double, triple, and quadruple bonds.
Example:
covalent1.jpg
In this example, a Phosphorous molecule is sharing its 3 unpaired electrons with 3 Chlorine atoms. In the end product, all four of these molecules have 8 valence electrons and satisfy the octet rule.
CHEMICAL BOND
ReplyDelete*also known as INTRAMOLECULAR FORCE
*involves interaction of atoms
*an attraction between atoms that allows the formation of chemical substances that contain two or more atoms.
TWO TYPES OF CHEMICAL BOND
IONIC BOND
*transfer of electron between metal and non-metal
atoms with 1 to 4 electron gives up its own electron to become stable and it become positively charged (+)
atoms with 5 to 7 electron accept another electron to become stable and it become negatively charged (-)
EXAMPLE:
ionic1 (2).jpg
In this example, Sodium(Na) transferred or gives up its electron to Chlorine to become stable;it becomes positively charged. In the other hand, Chlorine(Cl) accepts the electron from the Sodium to become stable;it becomes negatively charged.
COVALENT BOND
*sharing of electrons between two non-metals
the electrons are shared to one another to become stable
EXAMPLE:
File:Covalent.svg
In this example(CH4), the atoms only shared their electrons but not transferred.
IONIC PROPERTIES
Crystalline solids (made of ions)
High melting and boiling points
Conduct electricity when melted
Many soluble in water but not in non polar liquid
COVALENT PROPERTIES
Gases, liquids, or solids (made of molecules)
Low melting and boiling points
Poor electrical conductors in all phases
Many soluble in non polar liquids but not in water
Chemical Bonding
ReplyDelete( I N T R A M O L E C U L A R F O R C E )
--> define as the combination of two or more atoms. Atoms are combined to become STABLE.
-->this bond is caused by ELECTROSTATIC FORCE of attraction between opposite charges
-->since they attract by electrostatic force, the negative charge (electrons) that are orbiting the nucleus and the positively charged (protons) in the nucleus attract each other
IONIC BOND
--> is formed by a metal and a non-metal. These opposite ions attract each other.
-->characterized by high melting point and the ability to conduct electricity in the molten state
-->this bond has no definite shape
-->it has high boiling point
COVALENT BOND
-->consists of pairs of electrons shared by two atoms
-->has LOW polarity
-->the non-metals have similar electronegativities to attract electrons.
-->typically have low melting points, do not conduct electricity and are brittle
*These two bonds are also classified as "strong bonds"
CHEMICAL BONDING
ReplyDeleteAtoms are the basic building blocks of all types of matter. Atoms link to other atoms through chemicals bonds resulting from the strong attractive forces that exist between the atoms.
So what exactly is a chemical bond? It is a region that forms when electrons from different atoms interact with each other. The electrons that participate in chemical bonds are the valence electrons, which are the electrons found in an atom's outermost shell. When two atoms approach each other these outer electrons interact. Electrons repel each other, yet they are attracted to the protons within atoms. The interplay of forces results in some atoms forming bonds with each other and sticking together.
A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electrostatic force of attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction. The strength of chemical bonds varies considerably; there are "strong bonds" such as covalent or ionic bonds and "weak bonds" such as dipole–dipole interactions, the London dispersion force and hydrogen bonding.
TYPES OF CHEMICAL BONDING
Polar Covalent Bonds
Polar covalent bonds occur when two atoms share electrons unequally. Water is an example of a polar covalent compound. Because the oxygen atom has a stronger pull on the shared electrons, it develops a partial negative charge while the hydrogen atoms develop a partial positive charge. This is why water is excellent at dissolving polar substances.
An ionic bond is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions. Ionic bonds are formed due to the attraction between an atom that has lost one or more electron (known as a cation) and an atom that has gained one or more electrons (known as an anion). Usually, the cation is a metal atom and the anion is a nonmetal atom.
A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding.[1] For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full outer shell, corresponding to a stable electronic configuration.
POLARITY OF SUBSTANCES
ReplyDeletePolar Covalent Bond-- in this bond, the atom with higher electronegativity attracts the electrons more strongly, and that end of the other bond will have a partial negative charge.
The atom at the other end of the bond will have a positive charge.
HF and Water are polar molecules because the arrangement of the polar bonds is not symmetrically arranged.
Polar bonds may produce polar molecules. For hydrogen fluoride, there is a concentration of negative charge near the nitrogen and fluorine atoms and positive charge near the hydrogen atoms.
In oxygen- hydrogen bonds, there is a net concentration of negative charge near the oxygen atom and a slight positive charge near each hydrogen atom. Non polar covalent tends to be opposite.
An ionic bond is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions. Ionic bonds are formed due to the attraction between an atom that has lost one or more electron (known as a cation) and an atom that has gained one or more electrons (known as an anion). Usually, the cation is a metal atom and the anion is a nonmetal atom.
ReplyDeleteIt is important to recognize that pure ionic bonding - in which one atom "steals" an electron from another - cannot exist: all ionic compounds have some degree of covalent bonding, or electron sharing. Thus, the term "ionic bond" is given to a bond in which the ionic character is greater than the covalent character - that is, a bond in which a large electronegativity difference exists between the two atoms, causing the bond to be more polar (ionic) than other forms of covalent bonding where electrons are shared more equally. Bonds with partially ionic and partially covalent character are called polar covalent bonds. Nevertheless, ionic bonding is considered to be a form of noncovalent bonding.
Ionic compounds conduct electricity when molten or in solution, but not as a solid. They generally have a high melting point and tend to be soluble in water.
http://en.wikipedia.org/wiki/Ionic_bond
A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding.[1] For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full outer shell, corresponding to a stable electronic configuration.
ReplyDeleteCovalent bonding includes many kinds of interactions, including σ-bonding, π-bonding, metal-to-metal bonding, agostic interactions, and three-center two-electron bonds.[2][3] The term covalent bond dates from 1939.[4] The prefix co- means jointly, associated in action, partnered to a lesser degree, etc.; thus a "co-valent bond", in essence, means that the atoms share "valence", such as is discussed in valence bond theory. In the molecule H
2, the hydrogen atoms share the two electrons via covalent bonding.[5] Covalency is greatest between atoms of similar electronegativities. Thus, covalent bonding does not necessarily require the two atoms be of the same elements, only that they be of comparable electronegativity. Covalent bonding which entails sharing of electrons over more than two atoms is said to be delocalized.
Chemical Bond
ReplyDelete* an intramolecular force
*attraction force holding the electrons in an ion
* an attraction between atoms that allows the formation of chemical substances that contain two or more atoms
Two Types of Chemical Bond
1. Ionic- attraction between two opposite charged ions.An atom accepts an electron to become stable if it has 1-7 electrons, while an atom who has more electrons gives up electron since to become stable it needs 8 electrons. Transfer of electron from metal to nonmetal.
If an atom accepts electron its charge is negative (-)
If an atom gives up electron electron its charge is positive (+)
2. Covalent- sharing of electrons. is a chemical bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding.
Ionic Bond have one metal and one non-metal element.
Example of ionic bond:
NaBr - sodium bromide
KBr - potassium bromide
NaCl - sodium chloride
NaF - sodium fluoride
KI - potassium iodide
KCl - potassium chloride
CaCl2 - calcium chloride
Convalent Bond Example:
PCl3
CH3CH2OH
O3 - ozone
H2 - hydrogen
H2O - water
HCl - hydrogen chloride
CH4 - methane
NH3 - ammonia
CO2 - carbon dioxide
Ionic Properties-
ReplyDeleteIonic compounds form crystals.
Ionic compounds form crystal lattices rather than amorphous solids. Although molecular compounds form crystals, they frequently take other forms plus molecular crystals typically are softer than ionic crystals.
Ionic compounds have high melting points and high boiling points.
High temperatures are required to overcome the attraction between the positive and negative ions in ionic compounds. Therefore, a lot of energy is required to melt ionic compounds or cause them to boil.
Ionic compounds have higher enthalpies of fusion and vaporization than molecular compounds.
Just as ionic compounds have high melting and boiling points, they usually have enthalpies of fusion and vaporization that may be 10 to 100 times higher than those of most molecular compounds. The enthalpy of fusion is the heat required melt a single mole of a solid under constant pressure. The enthalpy of vaporization is the heat required for vaporize one mole of a liquid compound under constant pressure.
Ionic compounds are hard and brittle.
Ionic crystals are hard because the positive and negative ions are strongly attracted to each other and difficult to separate, however, when pressure is applied to an ionic crystal then ions of like charge may be forced closer to each other. The electrostatic repulsion can be enough to split the crystal, which is why ionic solids also are brittle.
Ionic compounds conduct electricity when they are dissolved in water.
When ionic compounds are dissolved in water the dissociated ions are free to conduct electric charge through the solution. Molten ionic compounds (molten salts) also conduct electricity.
Ionic solids are good insulators.
Although they conduct in molten form or in aqueous solution, ionic solids do not conduct electricity very well because the ions are bound so tightly to each other.
Covalent Properties-
ReplyDeleteMost covalent compounds have relatively low melting points and boiling points.
While the ions in an ionic compound are strongly attracted to each other, covalent bonds create molecules that can separate from each other when a lower amount of energy is added to them. Therefore, molecular compounds usually have low melting and boiling points.
Covalent compounds usually have lower enthalpies of fusion and vaporization than ionic compounds.
The enthalpy of fusion is the amount of energy needed, at constant pressure, to melt one mole of a solid substance. The enthalpy of vaporization is the amount of energy, at constant pressure, required to vaporize one mole of a liquid. On average, it takes only 1% to 10% as much heat to change the phase of a molecular compound as it does for an ionic compound.
Covalent compounds tend to be soft and relatively flexible.
This is largely because covalent bonds are relatively flexible and easy to break. The covalent bonds in molecular compounds cause these compounds to take form as gases, liquids and soft solids. As with many properties, there are exceptions, primarily when molecular compounds assume crystalline forms.
Covalent compounds tend to be more flammable than ionic compounds.
Many flammable substances contain hydrogen and carbon atoms which can undergo combustion, a reaction that releases energy when the compound reacts with oxygen to produce carbon dioxide and water. Carbon and hydrogen have comparable electronegativies so they are found together in many molecular compounds.
When dissolved in water, covalent compounds don't conduct electricity.
Ions are needed to conduct electricity in an aqueous solution. Molecular compounds dissolve into molecules rather than dissociate into ions, so they typically do not conduct electricity very well when dissolved in water.
Many covalent compounds don't dissolve well in water.
There are many exceptions to this rule, just as there are many salts (ionic compounds) that don't dissolve well in water. However, many covalent compounds are polar molecules that do dissolve well in a polar solvent, such as water. Examples of molecular compounds that dissolve well in water are sugar and ethanol. Examples of molecular compounds that don't dissolve well in water are oil and polymerized plastic.
Chemical polarity
ReplyDeleteIn chemistry, polarity refers to a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment. Polar molecules interact through dipole–dipole intermolecular forces and hydrogen bonds. Molecular polarity is dependent on the difference in electronegativity between atoms in a compound and the asymmetry of the compound's structure. Polarity underlies a number of physical properties including surface tension, solubility, and melting- and boiling-points.
A polar bond is a covalent bond between two atoms where the electrons forming the bond are unequally distributed. This causes the molecule to have a slight electrical dipole moment where one end is slightly positive and the other is slightly negative.
Polar bonds are the dividing line between pure covalent bonding and pure ionic bonding.
Examples:
Water is a polar bonded molecule.
a non polar bond is a type of chemical bond which has no positive or negative 'ends'.
Examples: Found in diatomic and homonuclear molecules, such as O2 and N2.
Polar molecules[edit]
The dipole moment of the water molecule.
A polar molecule has a net dipole as a result of the opposing charges (i.e. having partial positive and partial negative charges) from polar bonds arranged asymmetrically. Water (H2O) is an example of a polar molecule since it has a slight positive charge on one side and a slight negative charge on the other. The dipoles do not cancel out resulting in a net dipole. Due to the polar nature of the water molecule itself, polar molecules are generally able to dissolve in water. Another example includes sugars (like sucrose), which have many polar oxygen–hydrogen (-OH) groups and are overall highly polar.
The ammonia molecule, polar as a result of its molecular geometry. The red represents partially negatively charged regions.
The hydrogen fluoride, HF, molecule is polar by virtue of polar covalent bonds — in the covalent bond electrons are displaced towards the more electronegative fluorine atom. In the ammonia, NH3, molecule the three N–H bonds have only a slight polarity (toward the more electronegative nitrogen atom). However, the molecule has two lone electrons in an orbital, that points towards the fourth apex of the approximate tetrahedron, (VSEPR). This orbital is not participating in covalent bonding; it is electron-rich, which results in a powerful dipole across the whole ammonia molecule.
In the ozone, O3, molecule the two O–O bonds are nonpolar (there is no electronegativity difference between atoms of the same element). However, the distribution of other electrons is uneven — since the central atom has to share electrons with two other atoms, but each of the outer atoms has to share electrons with only one other atom, the central atom is more deprived of electrons than the others (the central atom has a formal charge of +1, while the outer atoms each have a formal charge of −1/2). Since the molecule has a bent geometry, the result is a dipole across the whole ozone molecule.
Nonpolar molecules
ReplyDeleteIn a molecule of boron trifluoride, the trigonal planar arrangement of three polar bonds results in no overall dipole.
A molecule may be nonpolar either when there is an equal sharing of electrons between the two atoms of a diatomic molecule or because of the symmetrical arrangement of polar bonds in a more complex molecule. For example, the boron trifluoride molecule (BF3) has a trigonal planar arrangement of three polar bonds at 120°. This results in no overall dipole in the molecule.
In methane, the bonds are arranged symmetrically (in a tetrahedral arrangement) so there is no overall dipole.
Examples of household nonpolar compounds include fats, oil, and petrol/gasoline. Therefore (per the "oil and water" rule of thumb), most nonpolar molecules are water-insoluble (hydrophobic) at room temperature. However, many nonpolar organic solvents, such as turpentine, are able to dissolve polar substances. When comparing a polar and nonpolar molecule with similar molar masses, the polar molecule in general has a higher boiling point, because the dipole–dipole interaction between polar molecules causes greater attachment. The most common form of such an interaction is the hydrogen bond, which is also known as the H-bond.
In the methane molecule (CH4) the four C–H bonds are arranged tetrahedrally around the carbon atom. Each bond has polarity (though not very strong). However, the bonds are arranged symmetrically so there is no overall dipole in the molecule. The diatomic oxygen molecule (O2) does not have polarity in the covalent bond because of equal electronegativity, hence there is no
POLARITY OF SUBSTANCES
ReplyDeleteNON-POLAR BONDS
• Formed by 2 atoms of similar elements.
*Type of covalent bond between two atoms in which electrons are shared equally.
When the bond formed an arrow with opposite direction, then it is considered as non-polar bond.
POLAR BONDS
• Formed by 2 atoms of different elements
*Type of covalent bond between two atoms in which electrons are shared unequally.
*The number of shared electrons depends on the number of electrons needed to complete the octet.
When the bond formed an arrow with the same direction, then it is considered as polar bond.
Also dipole will exist.
An arrow will form with the same direction when one of the atom’s electronegativity is greater than the other. It will attract additional electron towards itself. (The value of electronegativity can be found in the periodic table.)
CHEMICAL BONDING
ReplyDelete-a chemical bond is formed when separate atoms are brought together and the sharing or transfer of electrons
occurs.
-it can be weak or strong,depending on nature of the interactions.
Ionic bonding
-the removal of an electron from one atom, a process known as ionization,resulting the formation of an ionic bond.
-an ionic bond results from the strong electrostatic forces of attraction between the negatively charged anions and positively charged cations.
For example:
When atoms of sodium and chlorine are brought together,tablesalt(NaCl)is formed; a more proper representation might be Na+Cl-.
The formation of an ionic bond is the result of the competition for available electrons. A useful measure of this property is known as the electronegativity of an atom.
Covalent Bonding
-when the competition for bonding electrons is not severe as in the case of ionic bonding, a sharing of the available outer electrons of the atoms occurs and a covelent bond is formed.
-outer electrons that participate are termed valence electron.
Example
-two atoms of hydrogen bond ,each with valence of one,can combine to form diatomic H2,with two shared electrons forming a single covalent bond.
-the number of covalent bonds and atom can form is determined by its electric configuration.
-atoms can also share more than one electron pair to give multiple bonds.
POLARITY OF SUBSTANCES
ReplyDelete1. Polar
-unequal sharing of electrons
-arrows pointing in the same direction
EXAMPLE
Water Molecule
2. Nonpolar
-equal sharing of electrons
-symmetrical structure all hydro carbon are nonpolar
-arrows pointing in opposite direction
EXAMPLE
Ammonia (NH3)
Kerosene
“Like Dissolves Like”
Polar dissolves Polar
For example
*Salt dissolves in Water therefore Salt is Polar like Water.
*Salt cannot be dissolve in Oil because Oil is non-polar.
Non-polar dissolves Non-polar
For example
*Candle pieces is dissolved in Kerosene while on Water it just float, therefore Kerosene and Candle are both Non-polar.
Chemical bonding
ReplyDeleteChemical bond is an attraction that allows the formation of chemical substances which consist of two or more atoms
.It is also an attraction that maybe seen as the result of diffirent behaviors of the outermost electrons of an atom
.It is an association of the transfering and sharing of electrons between participating atoms.It is also referred as Intramolecular forces .
There are two types of chemical bond. Ionic bond and covalent bond .
Ionic bond is formed when Metallic atom donate valence electrons to non-metallic atoms. The resulting ions have opposite charges and attract each other into rigid lattices. Lattice referred as an array of object or points in a periodic pattern in two or three dimensions esp. an array of atoms and ions in a crystal. This bonding structures give high bond strength that provides brittle substances with high melting point and low conductivity.
For example:Sodium (Na) which has an atomic number 11 and Chlorine (Cl) which has an atomic number 17 will form an Ionic bond .Since Na is near Neon (Ne) that has an atomic number 10 and Na should loose 1 valence electron and Ne should gain or accept 1 valence electron to become stable while Cl which is near Argon(Ar) and Cl should gain or accept 1 valence electron to become stable , so the valence electron given by Na is simply taken by Cl.
Anothe type of Chemical bond is the Covalent bond.It Is formed when two non-mettalic atoms shared their valence elecrons .This is also formed when two non-metals have the tendency to gain electrons.
It tell us about the Electronegativity of atoms . Electronegativity is referred as the ability of an atom to attract electrons towards itself.
One type of covalent bond is the bonding of oxygen atoms .Since Oxygen has 6 valence electrons and in order to become stable it should accept or gain 2 valence electrons ,so two oxygen atoms bond by sharing one pair of electrons- this pair are what you called Bonding pairs and this bonding pairs will form a double bond . The remaining two pairs are what we called Lone pairs.
Chemical bond
ReplyDelete(Intramolecular force)
-The attraction force between any two atoms.
-The chemical attraction between atoms in a molecule.
• Intramolecular bonds are the chemical bonds that are formed or broken when a substance participates in a chemical reaction.
IONIC-transfer of electron (metal + metal).
COVALENT-sharing of electron (metal + nonmetal).
1. POLAR-unequal sharing of electron.
EX: water
2. NONPOLAR- equal sharing of electron.
EX: carbon dioxide
WAYS TO DETERMINE IF POLAR OR NONPOLAR THROUGH:
1. DIPOLES
-Presence of electrical charge.
-Partial+ & partial- charge in same direction.
Ex:
2. Through electronegativity
-getting its difference.
DIFFERENCE:
0-NONPOLAR (NP)
0.1-1.6-POLAR (P)
1.7 & ABOVE-IONIC
• BUT if the electronegativity is not the same with the dipoles, consider first the dipoles.
3. If it forms a symmetrical shape, it is a nonpolar (np).
4. If it is a hydrocarbon, it is a nonpolar (np).
-Hydrocarbons are substances that contain hydrogen and carbon.
REMEMBER:
LIKE DISSOLVES LIKE
-It means that polar dissolves polar and nonpolar dissolves polar.
Exception to the octet rule:
1. Incomplete Octet
-less than 8
Ex: Boron (B)
2. Expand Octet
-more than 8
Ex: Sulfur (S)
3. Odd no. of total electron
-when the valence electron of an element is odd
Ex: family 3 & 5
There are two types of chemical bonding: the IONIC and COVALENT bonding.....
ReplyDeleteAn IONIC BOND is the electrostatic force that holds ions together in an ionic compound.Consider,for example,the reaction between lithium and fluorine to form lithium fluoride,a poisonous white powder used in lowering the melting point of solders and in manufacturing ceramics.The electron configuration of lithium is 1s2 2s1,and that of fluorine is 1s2 2s2 2p5.When lithium and fluorine atoms come in contact with each other ,the outer 2s1 valence electron of of lithium is transferred to the fluorine atom......IONIC BOND holds the cations and anions in an ionic compound.
The other one is the COVALENT BOND...it is a bond in which two electrons are shared by two atoms......
.Covalent compounds are compounds that contain only covalent bonds.For the sake of simplicity,the shared pair of electrons is often represented by a single line.Thus,the covalent bond in Hydrogen molecule can be written as H---H.In a covalent bond,each electron in a shared pair is attracted to the nuclei of both atoms.This attraction holds the two atoms in H2 together and is responsible for the formation of covalent bonds in other molecules.
IONIC BONDING contains a metal and a non-metal element while COVALENT BONDING contains 2 non-metal elements.
A property that helps us distinguish a non-polar covalent bond from a polar covalent bond is ELECTRONEGATIVITY....the ability of an atom to attract toward itself the electrons in a chemical bond.
Covalent bond can be a POLAR(unequal sharing of electrons)or a NON-POLAR BOND(equal sharing of electrons)......
We can determine if a given compound is a Polar or a Non-polar bond through:
>>electronegativity difference between the two bonding atoms...
~If it’s EN difference is 0.1-1.6..it i a polar bond..
~If it’s E.N difference is 1.7 and above,it is considered as an Ionic bond.
>>direction of DIPOLES[partial (+)(lower E.N) and partial (-) charge(higher E.N).
~If the dipoles are on the same direction...then,it is a polar bond.
~If the dipoles are in an opposite direction...then,it is a non-polar bond.
Examples of POLAR BOND: H2O,NH3
Example NON-POLAR BOND: NH4
ONAL INFO.
>If the given compound contains a Hydrogen and Carbon molecules which was called as HYDROCARBONS...it is a non-polar bond.
*polar + polar or non-polar + non-polar...can be mixed and combined...[ex.salt+water]
*polar + non-polar cannot be mixed and combined[ex. candle+water]
‘LIKE DISSOLVES LIKE’
**Arianne Kate Borromeo
ReplyDeleteChemical Bond
A chemical bond is formed when separate atoms are brought together and sharing or transfer of electrons occurs. Chemical bonds can be weak or strong, depending on the nature of the interactions. The physical and chemical properties of most compounds are due, in large part, to these bonding forces.
Ionic Bonding. When two or more atoms combined, there is so called a competition for the available electrons to be completed. Its resulting formation involves the removal of electron from one atom. The ionic bond results from the strong electrostatic forces of attraction between charged anions and positively charged cations. Ionic bonding is common in organic compounds, where the charges are easily accommodated on relatively small ions. The formation of an ionic bond is the result of the competition for available electrons. A useful measure of this property is known as electronegativity of an atom. In general, a more electronegative element will take a larger share of any bonding electrons when forming a chemical bond. If a great disparity exists between the electronegativities of the atoms ina particular compound, the uneven sharing will likely result in a complete transfer of one or more electrons and the formation of an ionic bond.
Covalent Bonding. When the competition for bonding electrons is not severe as in the case of ionic bonding, a sharing of the available outer electrons of the atoms occurs and a covalent bond is formed. The outer electrons that participate readily are termed valence electrons. For example, two hydrogen atoms, each with a valence of one, can combine to form diatomic H₂, with two shared electrons forming a single covalent bond. As two atoms approach each other, the electron cloud of one “senses” the attractive force of the positive nucleus of the other atom. This attraction is countered, at short interatomic distances, by the repulsions of the two positive nuclei and the two electron clouds. The number of covalent bonds an atom can form is determined by its electron configuration. Many stable compounds result from electron sharing between atoms so that two electrons fill s orbitals and six electrons fill p orbitals, giving eight electrons in a full valence electron shell. Unequal sharing of electron pairs leads to bonding that is intermediate between ionic and covalent. When electronegativities are different, but not so different that an ionic bond forms, electrons stay closer to the more electronegative atom. In hydrogen chloride, HCl, for example, the more electronegative chlorine atom has a partial negative charge and the less electronegative hydrogen atom has a partial positive charge, creating a dipole and giving what is known as a polar bond.
Metallic Bonding. Due to the relatively low ionization potential of the metallic elements in the periodic table, electrons are easily removed and are mobile in the most metallic solids. The resulting positive ions occupy sites in an extended array in three dimensions, but the electrons are delocalized. The mobile electrons are responsible for many of the properties of these materials, such as their high thermal conductivity, strength, high melting points, high densities, color, and electrical conductivity
Hydrogen Bonding. Hydrogen atoms bonded to highly electronegative atoms have a relatively large partial positive charge. The attraction between such a hydrogen atom and a center of negative charge in another compound, often an unshared electron pair on nitrogen or oxygen, is known as a hydrogen bond. Though, only about 5% as strong as covalent bonds, hydrogen bonds are important to the physical and chemical properties of many compounds. The properties of water and the structure and function of many biochemical molecules, notably DNA, are largely determined by hydrogen bondng.
This comment has been removed by the author.
ReplyDeletePolarity of Substances
ReplyDeletePOLAR - Unequal sharing of electrons
NONPOLAR – Equal sharing of electrons
*There are 4 ways in determining the polarity of molecules:
1. Through its ELECTRONEGATIVITY
2. Direction of dipoles
3. Shape or structure (symmetrical or not symmetrical)
4. Molecular Geometry
*But there are also exceptions in determining the polarity of molecules:
1. INCOMPLETE OCTET – with incomplete number of electrons after sharing
Example: Be, B, Al, Id, Sn
2. EXPANDED OCTET – with more than 8 electron after sharing
Examples: P, S, Cl, Kr
3. WITH ODD NUMBER OF TOTAL ELECTRONS
*There are also rules to consider to determine the polarity of a molecule.
• All hydrocarbons are nonpolar
• All linear molecules are nonpolar
• All molecule with 0.1 - 1.6 electronegativity is polar
• All molecule with 1.7 and up electronegativity is nonpolar
But this two last statements are not always true to all molecules.
Ionic bond is just like giving or transfer of electron to one another. And it can be in a metalic or non metalic elements.For example like sodium chloride.
ReplyDeletesodium has 1 electron so it must transfer its electron yo chlorine to be stable.
covalent bond is sharing of electron they dont give up or transfer its electron.it can only be form in 2 nonmetalic elements.
Ionic Bonding: Ionic bonding is the complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates 2 oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the non-metal accepts those electrons to become a negatively charged anion. Ionic bonds require an electron donor, metal, and an electron accepter, nonmetal.
Ionic Bonding is observed because metals have few electrons in its outer-most orbital. By losing those electrons, these metals can achieve noble-gas configuration and satisfy the octet rule. Similarly, nonmetals that have close to 8 electrons in its valence shell tend to readily accept electrons to achieve its noble gas configuration. In ionic bonding, more than 1 electron can be donated or received to satisfy the octet rule. The charge on the anion and cation corresponds to the number of electrons donated or recieved. In ionic bonds, the net charge of the compound must be zero.
Covalent Bonding: Covalent bonding is the sharing of electrons between atoms. This type of bonding occurs between two of the same element or elements close to each other in the periodic table. This bonding occurs primarily between nonmetals; however, it can also be observed between nonmetals and metals as well.
When molecules have similar electronegativity, same affinity for electrons, covalent bonds are most likely to occur. Since both atoms have the same affinity for electrons and neither is willing to donate them, they share electrons in order to achieve octet configuration and become more stable. In addition, the ionization energy of the atom is too large and the electron affinity of the atom is too small for ionic bonding to occur. For example: Carbon doesnt form ionic bonds since it has 4 valence electrons, half of an octet. In order to form ionic bonds, Carbon molecules must either gain or lose 4 electrons. This is highly unfavorable; therefore, Carbon molecules share their 4 valence electrons through single, double, and triple bonds so that each atom can achieve noble gas configurations. Covalent bonds can include interactions of the sigma and pi orbitals; therefore covalent bonds lead to formation of single, double, triple, and quadruple bonds.
Nonpolar Covalent Bond
ReplyDeleteA bond between 2 nonmetal atoms that have the same electronegativity and therefore have equal sharing of the bonding electron pair.
Polar Covalent Bond
A bond between 2 nonmetal atoms that have different electronegativities and therefore have unequal sharing of the bonding electron pair.
polarity of molecule can be consider the ff.
1 there electronegetivity
2 direction of dipole
3 shape
4 molecular geometry
MOLECULAR GEOMETRY is the three-dimensional arrangement of atoms in a molecule.A molecule’s geometry affects its physical and chemical properties,such as melting point,boiling point,density,and the types of reactions it undergoes.In general,bond lengths and bond angles must be determined by experiment.
ReplyDeleteVSEPR(valence-shell electron-pair repulsion)>>approach to the study of molecular geometry......it accounts for the geometric arrangements of electron pairs around a central atom in terms of the electrostatic repulsion between electron pairs.
~~>>>if the lone pairs increases,the bond angle decreases.
~~>>>chemical bonds repel and move apart from each other.
Electron Pairs About a Central Atom (A) in a Molecule and Geometry of Some Simple Molecules and Ions in Which the Central Atom Has NO LONE PAIRS:
*LINEAR
>bonding pairs: 2
>example: BeCl2,HgCl2
>bond angle: 180°
*TRIGONAL PLANAR
>bonding pairs: 3
>example: BF3
>bond angle: 120°
*TETRAHEDRAL
>bonding pairs: 4
>examples: CH4,NH4+
>bond angle: 109.5°
*TRIGONAL BYPYRAMID
>bonding pairs: 5
>examples: PCl5
>bond angle: 90°,120°,180°
*OCTAHEDRAL
>bonding pairs: 6
>examples: SF6
>bond angle: 90°,180°
ADDITIONAL INFO.:
>>Substituent atoms-bond with the Central Atom
>>CENTRAL ATOMS-the one which has the greatest number of unpaired electrons.
TWO General Rules Govern the Use of The VSEPR model:
ReplyDelete1,As far as electron-pair repulsion is concerned,double bonds and triple bonds can be treated like single bonds.This approximation is good for qualitative purposes.However,we should realize that in reality multiple bonds are ‘’larger’’ than single bonds between two atoms,the electron density occupies more space.
2.If a molecule has two or more resonance structures,we can apply the VSEPR model to any one of them.Formal charges are usually not shown.
Nonpolar Bond - 2 atoms of similar element
ReplyDelete- molecules are electrically uniform
- symmetrical structure
- equal sharing of electrons
Polar - can be formed by 2 atoms of different elemys
- involves unequal sharing of electrons
Electronegativity - the ability of an atom to attract additional electron towards itself. The value can be found in the periodic table.
Parameter:
> electronegativity values ( difference ) " but not all the time "
> dipoles (dipole moment)
- presence of electrical charge
- partial positive and partial negative charge in same direction
> symmetrical/not symmetrical
MOLECULAR GEOMETRY
ReplyDelete-- determines the polarity
-- determines other property (boiling point,melting point....)
-- to minimize repulsion, the electron muts far from each other
1.LINEAR
>bonding pairs: 2
>example: BeCl2,HgCl2
>bond angle: 180°
2.TRIGONAL PLANAR
>bonding pairs: 3
>example: BF3
>bond angle: 120°
3.TETRAHEDRAL
>bonding pairs: 4
>examples: CH4,NH4+
>bond angle: 109.5°
4.TRIGONAL BYPYRAMID
>bonding pairs: 5
>examples: PCl5
>bond angle: 90°,120°,180°
5.OCTAHEDRAL
>bonding pairs: 6
>examples: SF6
>bond angle: 90°,180°
VSEPR Theory- " Valence Shell Electron Pair Repulsion Theory "
- basis of identifying and determining the shapes
- inable us to determine the shape of different molecule
** Central atom- with the greater number of unpaires electrons
** Substituent atoms- atoms that bond with the central atom
Non-Polar Molecule involves equal sharing of electrons ,2atoms of similar element ,molecules are electrically uniform and have a symmetrical structure while Polar Molecle involves unequal sharing of electrons ,formed by 2 atoms of diffirent element and have unsymmetrical structure.
ReplyDeleteThere are 3 factors to considered in determining the nature of a molecule , wheather it is Polar or Non-Polar.
One factor is the diffirence in its electronegativity , if it has a diffirence of zero it is considered Non-Polar and if it has a diffirence of 0.1 -1.6 it is considered Polar while if it has a diffirence of 1.7 and up it is considered Ionic.
For example:H2, since they are same atom and has the same electronegativity they are considered Non-Polar because 2.1minus 2.1 is equal to zero and therefore it is a Non-Polar molecule.
In the case of Carbon dioxide (CO2) it is considered Non-polar although its diffirence in Electronegativity is 1.0 because 3.5 the electronegativity of oxygen minus 2.5 the electronegativity of carbon is equal to 1.0.
In this time we will considered the other factor which is known as the cancellation of dipole.Dipole is referred as the partial negative and the partial positive charge. If we will write the Lewis Dot Structure of CO2 , The O will have the partial negative and C will have the partial positive . Since they are in opposite direction towards O because it is more electronegative than C ,there will be a cancellation of Dipoles .Therefore it is considered Non-Polar.
If there is a cancellation of Dipole the Molecule is considered Non-Polar and if there is no cancellation of Dipole it is considered Polar.
In H2O or water , it is considered Polar because there will be no cancellation of dipoles .In the Lewis Dot Structure of H2O , the Oxygen will be the central atom because it has the greater number of unpaired electrons and it will have the partial negative while the Hydrogen will have the partial positive .The dipoles will be in the same direction towards O since it is more electronegative than H.There will be no cancellation of dipoles and therefore it is considered a Polar Molecule .
In CH4 or Methane although we know that it is Non-Polar because it is a Hydrocarbon molecule due to the presence of H and C and there will be no cancellation of Dipoles because they are in the same direction towards carbon since it is more electronegative than Hydrogen but knowing its structure it`s symmetrical and having a symmetrical structure is considered Non-Polar.
If the molecule is NON-POLAR it structure is symmetrical while if it is unsymmetrical it is considered POLAR.
This factor is also considered in determining the nature of a molecule.
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ReplyDelete**Mae Andrea Lo
ReplyDeleteChemical Bonding
Chemical Bonding is formed when separate atoms are brought together and the sharing or transfer of electron occurs .
There are two types of chemical bonding, the ionic bonding and the covalent bonding.
Ionic Bonding is a chemical bond formed between oppositely charged atoms because of their mutual electrostatic attraction. The formation of an ionic bond is the result of the competition for available electrons. A useful measure of this property Is known as the electronegativity. ELECTRONEGATIVITY is the ability of an atom to attract additional electron towards itself. The value can be found in the Periodic Table.
Covalent Bonding is a chemical bond formed between atoms by sharing of electrons. The outer electrons that participate are termed valence electron. VALENCE Electron is a single electron or one of two or more electrons in the outer shell of an atom that is responsible for the chemical properties of the atom. Covalent Bond has two types: the polar which is the unequal sharing of electrons. Examples are H2O, HF and NH3. While Non-Polar is the equal sharing of electron. Example are H2, CH4 (Methane) and BF3.
A dipolar bond[1], also known as coordinate link[2], coordinate covalent bond[3], dative bond[4], or semipolar bond, is a description of covalent bonding between two atoms in which both electrons shared in the bond come from the same atom. The distinction from ordinary covalent bonding is artificial, but the terminology is popular in textbooks, especially those describing coordination compounds. Once such a bond has been formed, its strength and description is no different from that of other polar covalent bonds.
ReplyDeleteDipolar bonds occur when a Lewis base (an electron pair donor or giver) donates a pair of electrons to a Lewis acid (an electron pair acceptor) to give a so-called adduct. The process of forming a dipolar bond is called coordination. The electron donor acquires a positive formal charge, while the electron acceptor acquires a negative formal charge.
Contents
1 Examples
2 Coordination compounds
3 Important Points
4 See also
5 References
6 External links
Examples
Classically, any compound that contains a lone pair of electrons is capable of forming a dipolar bond. The bonding in diverse chemical compounds can be described as coordinate covalent bonding.
Carbon monoxide (CO) can be viewed as containing one coordinate bond and two "normal" covalent bonds between the carbon atom and the oxygen atom. This highly unusual description illustrates the flexibility of this bonding description. Thus in CO, carbon is the electron acceptor and oxygen is the electron donor.
Beryllium dichloride (BeCl2) is described as electron deficient in the sense that the triatomic species (which does exist in the gas phase) features Be centers with four valence electrons. When treated with excess chloride, the Be2+ ion binds four chloride ions to form tetrachloroberyllate anion, BeCl42-, wherein all ions achieve the octet configuration of electrons.
Coordination compounds
Dipolar bonding is popularly used to describe coordination complexes, especially involving metal ions. In such complexes, several Lewis bases "donate" their "free" pairs of electrons to an otherwise naked metal cation, which acts as a Lewis acid and "accepts" the electrons. Dipolar bonds form and the resulting compound is called a coordination complex, and the electron donors are called ligands. A more useful description of bonding in coordination compounds is provided by Ligand Field Theory, which embraces molecular orbitals as a description of bonding in such polyatomic compounds.
Chemical Bonding
ReplyDelete*A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms
*Attractive force existing between any two atoms
Two Types of Chemical Bonding
IONIC BONDING
-Transfer of electron from metal to non-metal
-Is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions
COVALENT BONDING
-Sharing of electrons between two or more non-metal
-A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms.
POLARITY OF SUBSTANCES
ReplyDeletePOLAR
-unequal sharing of electron
NONPOLAR
-equal sharing of electrons
THREE PARAMETERS
*electronegativity
*dipole
*shape
Dipole
*partial positive and partial negative charged
*the more electronegative-partial negative
*the lesser electronegative-partial negative
Molecular Geometry
ReplyDelete-- determines the polarity of substance
3 Parameters
1. Electronegativity
2. Dipole
3. Shape of molecule
*all LINEAR are non-polar
-- they are electron pair geometry
LINEAR-- two bonding pair moved in opposite directions, making an angle of 180 degrees with each other, the molecular geometry of its compound is linear.
ex.: Carbon dioxide
OCTAHEDRAL-- type of molecular geometry wherein six atoms align symmetrically. Its bond angle is 90 degrees.
ex.: Sulfur hexafluoride
TETRAHEDRAL-- a central atom is located at the center with four atom substituents that are located at the corners of a tetrahedron. Its bond angle is slightly less than 120 degrees.
ex.: Methane
TRIGONAL BIPYRAMIDAL-- has one atom at the center and five more atoms at hte corners of a triangular dipyramid. Its bond angle is less than 109.5 degrees.
ex.: Phosphorous pentachloride
TRIGONAL PYRAMIDAL-- has one atom at the center and three atoms at the corners of a trigonal base. Its bond angle is less than 109.5 degrees.
ex.: Ammonia
TRIGONAL PLANAR-- type of molecular geometry with ine atom at its center and three atoms at the corners of a triangle. The ideal bond angle for trigonal planar is 120 degrees.
ex.: Boron trifluoride
SQUARE PLANAR-- a central atom is surrounded by constituent atoms, which form the corners of a square on the same plane. Its bond angle is 90 degrees.
ex.: Sulfur dioxide
SQUARE PYRAMIDAL-- results when there are five bonds and one lone pair on the central atom of the molecule. Its bond angle is 90 degrees.
ex.: Bromine pentafluoride
T-SHAPED-- three bonds and two lone pairs at the central atom and form a T- shaped molecule. Its bond angle is less than 90 degrees.
ex.: Iodine trichloride
BENT-- an example of of bent molecular geometry is Water. Its bond angle is less than 120 degrees.
VSEPR Theory states that:
- bond angle decreases while the lone pair and bond pair increases
- chemical bond repel and move apart from each other after repulsion
SUBSTITUENT ATOMS-- they bond with central atom
Elements with Incomplete Octet
* Beryllium
* Boron
* Aluminum
* Gallium
* Indium
* Tin
Elements with Expanded Octet
* Phosphorous
* Sulfur
* Chlorine
* Krypton
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ReplyDeleteINTRAMOLECULAR FORCE
ReplyDelete-- also called van der Waals Force
-- a weak force
-- only exist in neighboring particles
-- responsible for the change of phase of molecules
-- makes substances become in a solid state
Factors Affecting the IMF :
-- speed of molecules
-- strength of IMF
--->The ELECTRONEGATIVITY essentially defines the intermolecular force.
--ability of an atom to attract additional electrons toward itself.
van der Waals Force-- weak, short-ranged electrostatic attractive forces between uncharged molecules, resulting from the interaction of permanent dipole moments.
---> named after Dutch theoretical physicist, Johannes Diderik van der Waals, who is famous for his work on an equation of state for gases and liquids.
3 Types of Intermolecular Bonding
** Hydrogen bonding-- a type of dipole-dipole bond wherein the electromagnetic interaction between polar molecules in which Hydrogen is bound to a highly electronegative atom ( Oxygen. Nitrogen, Chlorine and Fluorine )
---> they are about five times stronger than a regular dipole-dipole bond.
** Dipole forces-- it occurs between polar molecules. The electrons of the atom are drawn towards the side of the atom facing the positively charged part of the polar molecule.
---> they have permanent dipole
---> are stronger than London Dispersion Force
---> has a higher boiling point
** London Dispersion Force-- has the weakest force. It is the type of force acting between atoms and molecules. They are part of van der Waals Force.
---> it exists in nonpolar substances and has equal distribution of atoms
---> unlike the H-bond, it has only temporary dipoles (ex.:Methane)
---> named after German-American physicist, Fritz Wolfgang London, who contributed to the theories of chemical bonding of intermolecular forces.
Instanteneous-induced dipole-- occurs when one molecule with a permanent dipole repels another molecule's electron.
---> they have lower boiling point
---> easily evaporates/volatile
---> The higher the molar mass, the higher the boiling point
Coordinate covalent bond-- pair of electron that supplies only by one of the two atoms.
By JAN AIRISH BUENDIA
ReplyDeleteCHEMICAL BONDING
==an intramolecular force
==an attraction between atoms that allows the formation of chemical substances that contain two or more atoms.
==combining atoms to become stable occurs
TWO TYPES OF CHEMICAL BOND
IONIC BOND
_ bond between 2 ions which are formed from the transfer of electrons from one to another
_ composed of metal and non metal elements
Example:
NaCl (sodium chloride)
COVALENT BOND
_ they are formed by the sharing of electrons
_composed of 2 non metals
_ they are also poor conductors of electricity
by JAN AIRISH BUENDIA
ReplyDeletePOLARITY OF SUBSTANCES
>polarity of substances can be determined through:
-its electronegativity
-direction of dipole
-its shape
-its molecular geometry
POLAR
a type of covalent bond between two atoms in which electrons are shared unequally. Because of this, one end of the bond has a fractional negative charge and the other a positive charge.
NON POLAR
a type of covalent bond between 2 atoms in which electrons are shared equally.
EXEPTIONS:
INCOMPLETE OCTET
_have incomplete number of electrons after sharing
EXPANDED OCTET
_have more than 8 electrons after sharing
ODD NUMBER OF ELECTRONS
by JAN AIRISH BUENDIA
ReplyDeleteMOLECULAR GOEMETRY
Is the three-dimensional arrangement of the atoms that constitute a molecule. It determines several properties of a substance including its reactivity, polarity, phase of matter, color, magnetism, and biological activity.
LINEAR
BONDING PAIRS: 2
LONE PAIRS: 0
BOND ANGLE: 1800
EXAMPLE: CO2
TRIGONAL PLANAR
ONDING PAIRS: 3
LONE PAIRS: 0
BOND ANGLE: 1200
EXAMPLE: BF3
TETRAHEDRAL
BONDING PAIRS: 4
LONE PAIRS: 0
BOND ANGLE: 1O9.50
EXAMPLE: CH4
TRIGONAL BIPYRAMIDAL
BONDING PAIRS: 5
LONE PAIRS: 0
BOND ANGLE: 900, 1200, 1800
EXAMPLE: PCl5
OCTAHEDRAL
BONDING PAIRS: 6
LONE PAIRS: 0
BOND ANGLE: 900, 1800
EXAMPLE: SF6
BENT
BONDING PAIRS: 2
LONE PAIRS: 1
BOND ANGLE: 1190
EXAMPLE: SO2
SQUARE PLANAR
BONDING PAIRS: 5
LONE PAIRS: 1
BOND ANGLE: 84.80,1800
EXAMPLE: XeF4
by JAN AIRISH BUENDIA
ReplyDeleteMOLECULAR GOEMETRY
Is the three-dimensional arrangement of the atoms that constitute a molecule. It determines several properties of a substance including its reactivity, polarity, phase of matter, color, magnetism, and biological activity.
LINEAR
BONDING PAIRS: 2
LONE PAIRS: 0
BOND ANGLE: 180
EXAMPLE: CO2
TRIGONAL PLANAR
ONDING PAIRS: 3
LONE PAIRS: 0
BOND ANGLE: 120
EXAMPLE: BF3
TETRAHEDRAL
BONDING PAIRS: 4
LONE PAIRS: 0
BOND ANGLE: 1O9.5
EXAMPLE: CH4
TRIGONAL BIPYRAMIDAL
BONDING PAIRS: 5
LONE PAIRS: 0
BOND ANGLE: 90, 120, 180
EXAMPLE: PCl5
OCTAHEDRAL
BONDING PAIRS: 6
LONE PAIRS: 0
BOND ANGLE: 90, 180
EXAMPLE: SF6
BENT
BONDING PAIRS: 2
LONE PAIRS: 1
BOND ANGLE: 119
EXAMPLE: SO2
SQUARE PLANAR
BONDING PAIRS: 5
LONE PAIRS: 1
BOND ANGLE: 84.8,180
EXAMPLE: XeF4
Chemical Bonding
ReplyDelete-Physical chemists were able to establish the reason why certain changes happened naturally or spontaneously.All systems in the universe tend to move toward a state of maximum stability.With the help of chem-connect,I further understand concepts why chemical combination of atoms occur.I learn atoms combine to be more stable.In order to be stable,they need 8 electrons according to Octet Rule.The combined atoms in a compound are said to be chemically bonded.The attractive force is called Chemical Bond.The great example of this which we perform in promotion in the community is Dye Dying.Chem-connect explains why the colors we used forms a design.The audience also learn concepts involving Chemical Bonding.I also learn the two types of chemical bonding-Ionic and convalent.Chem-connect truly help me and people in the community in understanding Chemistry.
My Reflection:Chem Connect
ReplyDeleteFor me, chem connect project aims to make students and others to understand chemistry and its contributions in our daily lives. it also explain chemistry in simple way so that it is easy for the person to understand, since we don't need long explanation but a short but all the thing we should know is in it. it is also away of exchanging ideas, using modern technology as an instrument of sharing ideas and the promotion chemistry products.This project helped me in understanding chemistry. even though im not good in chemistry but this project explain it well and simple which is easier to understand. Chemistry is very functional, it is the reason how we made the things that helps us in our daily lives. For example, like detergents, medicine, and make up etc. It also helped us in promoting applied chemistry to our community like showing them experiments that could be used in making income. we shared our ideas to them making understand chemistry can be helpful in our lives.
My Reflection: Chem-ConnectChemistry helps in our daily life. Chemistry is the physical science that investigates occurring in our macroscopic work. Everything you see, you feel is made up of Chemistry. One project of Chemistry is Chem.-Connect through this project the students are promoting the leanings they learned from their everyday class. Chem. - Connect has process, over viewing the topic, formulating some questions showing a video clip related to the lesson, discussing the topic and applying or promoting it in school and community.
ReplyDeleteI really understand Chemistry through Chem.-Connect. Every topic, Sir really explained every single idea. I learned a lot and gained some knowledge through Chem.-Connect. I can help other people. I can share my knowledge to them. I also help my co-schoolmate. They will know that everything is made up of Chemistry. They will also know some applications of it. This application helps the people to gain some money and experiences. It is natural and we can avoid some chemicals. We can protect our body from some chemicals found in the everyday we used. Promoting Chemistry in community is helpful to them and for us. Through serving as a group in community, even we haven’t enough knowledge to share it to others but as we combine it, we can help a community and every single idea is equal to gold. That gold cost thousands, millions that can help our self not only our self but our community.
intermolecular force
ReplyDelete-force that is present b/w molecules
-weak force
-change in phase of molecule
-cohesion/cohesion forces
-w/out this all matter will be in gas state
vander waals forces
-johannes vander waals
intramolecular force
-covalent force b/w atoms
-strong force
london dispersion forces- 0.5 (nonpolar covalent)
- all hydro carbon
- weakest
-instantaneous
- nonpolar molecule
- induced dipole
dipolar forces- -5 ^ 1.7 (polar covalent)
-stronger than london dispersion forces
-dipole permanent
-higher boiling point
hydrogrn bond
- h atom is bonded w/ highly electronegative atom O, N, Cl
- strongest force
phase changes
- weak forces are easily broken not the ionic and covelent bond
cohesion- similar particles
adhesion- dissimilar particles
In chemistry, the molar mass M is a physical property. It is defined as the mass of a given substance (chemical element or chemical compound) divided by its amount of substance.[1] The base SI unit for molar mass is kg/mol. However, for historical reasons, molar masses are almost always expressed in g/mol.
As an example, the molar mass of water is approximately: M(H2O) ≈ 18 g⋅mol−1
REFLECTION: " Chem-Connect "
ReplyDeleteChemistry is a big help to our everyday lives. It is a physical science that investigates the molecular reasons for the process occuring in our macroscopic world. Everything that you can see in this world,you can feel,smell and taste is made up of chemistry. There are a lot of studies that will help us in dealing Chemistry.
Our chem-connect project is made because through this, the lessons we had learned can be applied in our lives and can share it to the community. We can promote the learning we had learned from Chemistry. So that this project will be interesting, Chem-connect can be shown through video clips related to the topic, formulating questions from the video, giving information about the topic and especially, applying the lessons through an experiment. We should assure that the participants learned something about the topics discussed.
In every topic we have discussed, I learned a lot of lessons that can help me in my daily living. Sir discussed every topic clearly. And every discussion I learned something new and different. I learned more new interesting facts and lessons about Chemistry through this project. The project give me ideas that will be a big help to mu schoolmates and community. Through our understanding, we can made an application regarding the topic. The practical applications we made can help the people in the community save time, money and effort. They can also gain money and fun experiences. Those experiments can be natural or synthetic but of course we can't avoid to put chemical to those experiments. But we can assure you that it can help the people save money, time and effort but can gain a lot of experience and learnings. Promoting Chem-connect to the community is a good help to the people who want to save moneys but want to learn something new about Chemistry. For us, it is a pleasure to share and help the people in the community. Though we're not that professional in explaining and giving them an information but still the ideas in our minds and the lessons we had learned can help us in giving them an explanations of the application. Promoting this project is a big help to the people who want to save money, gain some learnings and ideas.
Chemistry has a very important part in our lives and in the whole universe. It is important to know the benefits of the lessons in Chemistry. So as a student, it is important to have Chem-connect project as an application to the lessons we learned and share/promote it to others.
Beryllium has 2 outer electrons because it is in group 2. It forms bonds to two chlorines, each of which adds another electron to the outer level of the beryllium. There is no ionic charge to worry about, so there are 4 electrons altogether - 2 pairs.
ReplyDeleteIt is forming 2 bonds so there are no lone pairs. The two bonding pairs arrange themselves at 180° to each other, because that's as far apart as they can get. The molecule is described as being linear.
Three electron pairs around the central atom
The simple cases of this would be BF3 or BCl3.
Boron is in group 3, so starts off with 3 electrons. It is forming 3 bonds, adding another 3 electrons. There is no charge, so the total is 6 electrons - in 3 pairs.
Because it is forming 3 bonds there can be no lone pairs. The 3 pairs arrange themselves as far apart as possible. They all lie in one plane at 120° to each other. The arrangement is called trigonal planar.
Four electron pairs around the central atom
There are lots of examples of this. The simplest is methane, CH4.
Note: Elsewhere on the site, you will find the shape of methane worked out in detail using modern bonding theory. Here we are doing it the quick and easy way!
If you are interested in the bonding in methane you can find it in the organic section by following this link, or in a page on covalent bonding by following this one.
Carbon is in group 4, and so has 4 outer electrons. It is forming 4 bonds to hydrogens, adding another 4 electrons - 8 altogether, in 4 pairs. Because it is forming 4 bonds, these must all be bonding pairs.
Four electron pairs arrange themselves in space in what is called a tetrahedral arrangement. A tetrahedron is a regular triangularly-based pyramid. The carbon atom would be at the centre and the hydrogens at the four corners. All the bond angles are 109.5°.
Five electron pairs around the central atom
A simple example: phosphorus(V) fluoride, PF5
(The argument for phosphorus(V) chloride, PCl5, would be identical.)
Phosphorus (in group 5) contributes 5 electrons, and the five fluorines 5 more, giving 10 electrons in 5 pairs around the central atom. Since the phosphorus is forming five bonds, there can't be any lone pairs.
The 5 electron pairs take up a shape described as a trigonal bipyramid - three of the fluorines are in a plane at 120° to each other; the other two are at right angles to this plane. The trigonal bipyramid therefore has two different bond angles - 120° and 90°.
Six electron pairs around the central atom
A simple example: SF6
6 electrons in the outer level of the sulphur, plus 1 each from the six fluorines, makes a total of 12 - in 6 pairs. Because the sulphur is forming 6 bonds, these are all bond pairs. They arrange themselves entirely at 90°, in a shape described as octahedral.
Two slightly more difficult examples
XeF4
Xenon forms a range of compounds, mainly with fluorine or oxygen, and this is a typical one. Xenon has 8 outer electrons, plus 1 from each fluorine - making 12 altogether, in 6 pairs. There will be 4 bonding pairs (because of the four fluorines) and 2 lone pairs.
There are two possible structures, but in one of them the lone pairs would be at 90°. Instead, they go opposite each other. XeF4 is described as square planar.
Each lone pair is at 90° to 2 bond pairs - the ones above and below the plane. That makes a total of 4 lone pair-bond pair repulsions - compared with 6 of these relatively strong repulsions in the last structure. The other fluorine (the one in the plane) is 120° away, and feels negligible repulsion from the lone pairs.
The bond to the fluorine in the plane is at 90° to the bonds above and below the plane, so there are a total of 2 bond pair-bond pair repulsions.
The structure with the minimum amount of repulsion is therefore this last one, because bond pair-bond pair repulsion is less than lone pair-bond pair repulsion. ClF3 is described as T-shaped.
My Reflection
ReplyDeleteFirst of all, the chem.-connect project is about helping us understand and love chemistry. It helps us know some practical application that will help us in our daily living. It also helps the community to know some application that will help them earn a living.
This chem.-connect project let me understand and love chemistry. This makes my understanding about chemistry easy for I found it fun and every time there is an experiment, I am exploring new ideas and I have some questions that the teacher immediately explained. It also helps me know some practical application. This practical application helps me in my daily living. For example is the charcoal made of cornstarch. This is a long-lasting charcoal for when I used it today; I can still use it tomorrow and the other day. It is also easy to be lighted. With this charcoal, I can save money for I am not going to buy charcoal everyday. The last is that it helps me to promote some practical application in our community. With this, it can help them earn a living. One example of it is natural mango shake. It can be their business for it is more delicious than the mango shake made of powder. Aside from it, it is healthier for it is made from the mango fruit. They can also substitute the mango of different fruit like banana, avocado, etc. with this, their not just earning but they are also helping the costumer to become healthy.
I am so thankful to this chem.-connect project for it helps me a lot. It helps me understand and love chemistry. It also helps me know some practical application that helps me save money and lastly, it helps the community earn a living and make the costumer healthy. That’s why, I am very thankful to the chem.-connecting project.
Thank you so much!!
After we have discussed the chem connect project ive realized how chemistry really worked in our daily living. For example in the kitchen,ofcoures before doing any move,we must have any knowledge of the materials or ingredients we are going to use. In this case,the concept of polarity of substances are being contained . I'll site another example,there are some cases that children and other people become curious of some tthing,like why insects floats in water,why droplets of water become spherical in shape.The answer to this question cant be answered by people who do not take chemistry in there lives. This explains that there is something working on it,this is what we call intermolecular forces wherein those forces are the weak forces.there are 3 kinds of weak forces,the london dispertion,dipole forces and h-bond.
ReplyDeleteChemistry concepts really explains everything,though we may think that some cases are really imppossible to explain.
The chemconnect project gives enough knowledge to the students about different words, equation or explanation. In this project, I learn what are different types, description, equation and the history of chemistry, especially about chemical bonding. It is useful in my daily living because I know what are the things have inside, for ex. When you are cooking you already know when can you mixed it. Chemistry helps me to promote it in community because you are using technical words, new style in presenting a finished product. In understanding chem. At first, it is difficult but you will realize that is easy. In chemical bonding, I learn that ionic involves transferring of electrons and covalent bond involves sharing of electrons to make an element stable. I like this kind of project because it involves technical strategies like representing the output by using a power point and I enjoy some experiments and in this project, it practice and challenge our mind of what does thing can do to ourselves and our community. I learn something that can help In my daily living like mixing some chemicals or substances of what will be the first and the last to put and the observation of what is the effect that will come out after doing an experiment and it helped me to be active and do my work faster. In power point, it has sound effects that make the audience not to be bored. In games, even though last time we lost to do it because we lack time I think it would be the enjoying part because I think the even observer will participate about it, all in all, through chemconnect I will understand about chemistry.
ReplyDeleteadrian bruto : My Reflection
DeleteIntermolecular Forces
ReplyDelete- is a weak force
- exist between neighboring molecules
- hold the molecules together
- Vander Waals Forces- Dutch Scientist Johannes Diderick Vander Waals
*Impt* - responsible for the change in the phase of molecules.
- All matters will be in a gaseous phase/state if there’s no IMF
- responsible for solubility
Three Types of IMF
• London dispersion forces – exist in all molecules
( EN- less than 0.5)
- weakest
- volatile liquids- easily evaporates
- Lowest boiling point
-instantaneous – induced dipole
- there is a result in small fluctuations of electron clouds
• Hydrogen bond – a type of dipole-dipole
- five times stronger than regular dipole-dipole bonds
- a type of force wherein H atoms are bonded to highly electronegative atoms O, N,
- strongest among the three
• Dipole-dipole – (polar covalent) 0.5-1.7
- exist om polar molecules
- presence of permanent dipole
- stronger due to the presence of permanent dipole
**The higher the molar mass, the higher the boiling point.**
Cohesion – exist b/w similar particles (similar surfaces)
Adhesion – dissimilar particles
MOLECULES IN WHICH THE CENTRAL ATOM HAS ONE OR MORE LONE PAIRS
ReplyDelete>LEGEND:
~COM-class of molecule/formula
~BP-bonding pairs
~LP-lone pairs
~BA-bond angle
~AEP-arrangements of elctron pairs
*BENT
~COM-AB2E
~no. of BP-2
~no. of LP-1
~BA-119⁰(120⁰)
~ex.-SO2
~APE-trigonal planar
*TRIGONAL BIPYRAMIDAL
~AB3E
~3
~1
~less than 109.5⁰(107⁰)
~NH3
*BENT
~AB2E2
~2
~2
~104.5⁰
~H2O
~tetrahedral
*T-SHAPED
~AB3E2
~3
~2
~90⁰,180⁰
~CLF3
NOTES:
>the presence of the lone pairs decreases the bond angle of a molecule.
>FORMULA:ABE
>SO2 has a COORDINATE COVALENT BOND which is a pair of electron supplied only by one of the 2 atoms.
>CENTRAL ATOM:if the 2 molecule atom have the same no. of unpaired electron,consider the electronegativity
:the lesser the electronegativity is the central atom
INTERMOLECULAR FORCES
ReplyDelete>exists between molecules
>weak forces
>Van der Waals forces
*importance: change in phase of molecules
*TYPES
•LONDON DISPERSION FORCES
~attractive forces that arise as a result of temporary dipoles induced in atoms or molecules
~exists in all molecules but are esp. impt. tin non-polar covalent molecules
~weakest
•DIPOLE-DIPOLE FORCES
~attractive forces between polar molecules
~(polar covalent)0.5-1.7
•HYDROGEN BOND
~about 5 times stronger than regular dipole-dipole
~interaction between the H atom in a polar bond,such as N-H,O-H,or F-H and an electronegative O,N, or F atom.
>>>notes<<<
*the lower the IMF,the lower the boiling point.
*the higher the molar mass,the higher the boiling point
*gaseous state
Chemical Bonds are attractions between two or more atoms, which allow them to create chemical substances/compounds These bonds are formed by the
ReplyDeleteelectromagnetic forces between the
atoms, which can be caused for a
few reasons, including the sharing
or transfer of electrons (ionic/covelant bonds) These different types of bonds are
very important to the world of chemistry because...
1 Chemical bonds are used when
creating chemical compounds. These chemical compounds are
important as most substances today
are made from chemical compounds.
2 The different types of chemical bonds determine the different physical properties of the compounds that they create. For example, chemical
compounds with ionic
bonds have high melting
points.
3 Like physical properties, chemical bonding also affects/determines the chemical properties of a chemical compound
4With the use of chemical bonds, we can create chemical compounds that allow us to find new substances. These substances can be used to in new technology, medicine, and products Overall, with these compounds, we can advance into the future of chemistry and science Chemical bonds are extremely important to chemists, scientists, and everyday people. They create substances/compounds that everyone uses, even if they aren't aware of it. In general, without chemical bonds, life would be completely different. In all likely hood, there would be no life, as chemical bonds are so important. Chemical Bonds are what hold the world together.
So,because of chemical bonding humans can create anything and wr can define the properties of it....
Chemical bonds are what keep the atoms in a molecule together, without them you won't exist, the tables and chairs and anything visible would no exist. No compounds would exist but because of the way atoms are held together these bonds exist. It is impossible for them not to make bonds with their current structure.Thats why we have furnitures and other things in our homes or surroundings.
ReplyDeleteWithout the chemical bonding,there will also be no such things exists in this world.Furnitures,clothings,medicines,houses,buildings,and so on are made through chemical bonding.Even the smallest things we see wherever is made of chemical bonding.Human life would be useless iof there will be no chemical bonding......
As for the people who doesnt know yet about chemical bonding,ionic bond is the transfer of electrons from metal to non metal elements while the covalent bonding is the sharing of electrons between nonmetals.the covalent has two types;the polar which is the unequal sharing of electrons and the nonpolar with equal sharing of electrons.
ReplyDeleteit is important for us to know its significance, with the help of that we can determine the bond formed in a substance we usually have.some substances contains elements or compounds that forms a bond.
MY REFLECTION:)
ReplyDeleteChemistry is the study of the properties of matter and the changes it undergoes.Compared with other subjects,chemistry is commonly perceived to be more difficult
Chemistry is very useful to our daily lives.That's why I'm so glad that we had a CHEM.CONNECT PROJECT.
with the help of our teacher,Mr.Ronaldo Reyes.With the help of this,I was able to understand and learned more about chemistry.How it affects our life and it's advantages or benefits to us.
In chem.connect project,the topics are really discussed well.Just like the "Intramolecular Forces" wherein it explains about ionic and covalent bond.Also with the "Molecular Geometry" which shows the arrangements of atoms in a molecule. "Intermolecular Forces" also,which has 3 types:the london dispersion,dipole-dipole and hydrogen bond.Eventhough this words/phrases are new to me,I was able to understand then while discuss by our teacher.Not only that!It's amazing that we had a chem.connect project wherein we are promoting chemistry to our dear neighbors in our barangay.We taught them some practical applications on products like making toothpaste,charcoal,and hand sanitizer by just using such cheaper ingredients/materials for this.We enjoyed this kind of project given to us.
Chemistry help us in any way.Like for knowing how a product was made and what properties of ingredients are used to make a particular product.Eventhough it's hard for me to learn about it very well after every discussion,I always try my best to understand chemistry............
.
What a great experience I ever had!! Promoting chemistry subject in a community is such a difficult thing to do and being a facilitator is such an honor and also a priviledge but through our chem.-connect project , It really feels amazing .I was very nervous at first but when we started the program I was very happy because there are many participants who are willing to listen to us for additional knowledge and learning .
ReplyDeleteChemistry facts and tricks were given to the participants .The importance of chemistry were discussed by the facilitator and practical application of chemistry were done and enjoyed by the participants such as making Alovera Gel, Charcoal which is three times longer than the ordinary one , floam and especially mango shake which can be apply or practice in the community that would help them to gain additional profit and money to sustain their daily living . It was really overwhelming knowing that your fellow kabarangays once lend their ears to you to acquire additional knowledge and also skills.Also considered magics but with scientific basis were introduced and through chem.-connect project many science specifically chemistry principle were explained, like the mixture of denatured alcohol and water which water comes first to avoid exothermic reaction and one participant was challenge to offer her money to be put on the said mixture and then burn it .The participants were really shocked and amazed because the money didn`t burn but with the knowledge of chemistry it was carefully explained that the process of combustion causing the money to become not flammable is responsible to it.
Through our chem.-connect project , it gives me a clear understanding about chemistry which made me conclude that chemistry is such a difficult yet very exciting , enjoyable and interesting subject and it is not only a responsibility of every individual to study chemistry rather it gives them the skills and learning that made them to become conscious in everything around us which are mostly a product of chemistry and it gives me additional knowledge , skill , experience and learning. In this case , I should say CHEMISTRY tremendously make me feel alive and born again.
Polarity of a substance is important in a way that we can identify the properties of a substance and the charge of a substance.Example is the water,the polarity of water allows two important things to happen (or not happen) in living organisms for survival.
ReplyDelete-First, since water is polar, it has an unequal distribution of charge. This means that water molecules are slightly positive and negative. This quality is important because that makes water a good solvent (it can dissolve many things). Other polar compounds and ions can easily be dissolved in water because polar + polar = even distribution of charge, and ions have a charge, so it's attracted to the opposite charge on the water molecule.
The ability of water to dissolve many solutions is essential in organisms. In the bloodstream, for example, sugars and other nutrients are dissolved so that the blood cells can carry it to cells in the body. If sugars weren't dissolved, they couldn't reach cells.
-Second, the polarity of water is important in repelling nonpolar compounds. Nonpolar compounds don't dissolve well in water (like how oil, a nonpolar solution, forms "beads" in water). This is important to cell membranes in the body. The shape and function of cell membranes depend on the interaction of polar water with nonpolar membrane molecules.
Polarity
ReplyDeletePolarity in organic chemistry refers to a separation of charge and can describe a bond or an entire molecule. Experimentally, bond polarity is measured by its dipole moment. Bonds connecting atoms of different electronegativity are polar with a higher density of bonding electrons around the more electronegative atom giving it a partial negative charge (designated as d-). The less electronegative atom has some of its electron density taken away giving it a partial positive charge (d+).
We have seen that atoms differ in their capacity to "hold onto" their electrons; some gain electrons, some lose electrons. Certain atoms, oxygen and nitrogen, for example, do not have sufficient electron-attractive power to become fully charged negative ions.
However, the attractions of electrons is sufficiently great so that, when covalently bonded to hydrogen, the electrons are not equally shared between the two nuclei. The electrons tend to spend more time around the oxygen nucleus and consequently less time around the hydrogen nucleus. This means that one portion of a molecule is slightly positive or slightly negative in relation to another portion of the same molecule. When such an uneven distribution of charge occurs, the molecule is said to exhibit polarity. The molecule has a positive and a negative end, separated from eachother like the poles of a bar magnet. Because this is not a full -1 or +1 charge but a smaller charge, it is represented as delta positive or delta negative.
polarity
ReplyDeleteThe significance of molecular polarity to the biological sciences come from two main areas: First, polar molecules tend to become oriented with respect to other molecules. Because of this, polar molecules are important in helping to establish the three-dimensional structure or orientation of other larger molecules. For example, molecules of fatty acids (Chapter 8), found in all living matter are composed of a nonpolar carbon chain with a polar carbon-oxygen group (COOH) at one end. When placed in water, the polar ends of the fatty acid molecules are attracted to water molecules, which are also polar. The nonpolar carbon chains are at the same time repelled by the water. As a result, fatty acid molecules are oriented on the water's surface.
Of particular importance to living things is the orientation of phospholipid molecules, which are a combination of a fat molecule with a phosphate group. Phospholipids are among the most important parts of cell membranes. They tend to become oriented on surface or boundary regions in a manner similar to the fatty acids on water. It is partly in this way that cell membranes are given a distinct structure.
Second, polarity is important in understanding both the geometry and the chemical characteristics of large molecules, such as proteins. Proteins are so large that they may possess a number of polar groups on one molecule. Polar groups, like radicals (Section 3-4), are simply groups of atoms which bear as a unit a partial positive or a partial negative charge. The specific geometry of proteins exists in part because polar groups on one part of the molecule attract polar groups on another part of the same molecule. This stabilizes the specific twisting and folding of the molecule which is all-important to the chemical characteristics it displays.
Polarity thus tends to bring small molecules, or specific regions of large molecules, into definite geometric relation. In this way, the chemical bonding between individual molecules or between specific portions of large molecules is brought ab. Hydrogen bonds are produced by the electrostatic attraction between positively (partially)out more easily.
In living organisms, one of the most common types of chemical bonds produced by polar attraction is the hydrogen bond charged hydrogen atoms (protons) on one part of the molecule, and negatively charged atoms of oxygen or nitrogen on the same or another molecule. The oxygen and nitrogen atoms are partially negatively charged because their nuclei attract large numbers of electrons around them. Because the hydrogen bond occurs between polar regions of a molecule, it is, like all polar attractions, relatively weak.
A simple example of hydrogen bonding can be seen between water molecules. The hydrogen atoms of one water molecule form a hydrogen bond with the oxygen atom of the adjacent molecule. Polar molecules, such as fatty acids, tend to orient themselves in respect to other polar molecules. Here the molecules of a fatty acid line up in a specific fashion on the surface of water. The COOH groups are in the water (also polar) and the carbon chains stick out into the air.
molecular geometry
ReplyDeleteMolecular geometry or molecular structure is the three-dimensional arrangement of atoms within a molecule. It is important to be able to predict and understand the molecular structure of a molecule because many of the properties of a substance are determined by its geometry.
The Valence Shell, Bonding Pairs, and VSEPR Model
The outermost electrons of an atom are its valence electrons. The valence electrons are the electrons that are most often involved in forming bonds and making molecules.
Pairs of electrons are shared between atoms in a molecule and hold the atoms together. These pairs are called "bonding pairs".
One way to predict the way electrons within atoms will repel each other is to apply the VSEPR (valence-shell electron-pair repulsion) model. VSEPR can be used to determine a molecule's general geometry.
the molecular geometries are:
linear
bent
trigonal planar
tetrahedral
trigonal bipyramidal
octahedral
trigonal pyramid
seesaw
t-shape
VSERP THEORY ( Valence shell electron pair repulsion theory)-states that as the bonding and lone pair increases the bond angle decreases. The premise of VSEPR is that the valence electron pairs surrounding an atom mutually repel each other, and will therefore adopt an arrangement that minimizes this repulsion, thus determining the molecular geometry. The number of atoms bonded to a central atom plus the number of lone pairs of its nonbonding valence electrons is called its steric number.
ReplyDeleteMolecular Geometry –is the three –dimensional arrangement of the atoms that constitute a molecule and is the shape of a molecule and can be used to determine specific symmetry elements present ,which in turn can predict IR and Raman bending or stretching models which can help verify ,spectroscopically , the structure of the compound of interest .The Molecular geometry of a compound can be used to help make predictions about crystal structures ,dipole moment ,reactivity ,bond ,lengths and angles and can be predicted based on the elements present ,the coordination number and the orbital hybridization.
Molecular Geometry Bonding Pair Lone Pair Bond Angle(degrees) Example
ReplyDeleteLinear 2 0 180 CO2
Trigonal
Planar 3 0 120 BF3
Bent 2 1 119 SO2
Trigonal
Pyramidal 3 1 107 NH3
Tetrahedral 4 0 109.5 CH4
Trigonal
Bipyramidal 5 0 90,120,180 PCl5
Octahedral 6 0 90,180 SF6
Square
Planar 4 2 90,180 XeF4
1. In a Linear Model - atoms are connected in a straight line. The bond angle is set at 180 degrees .A Bond angle is very simply the geometric angle between two adjacent bonds .
2. Trigonal Planar –triangular and in one plane .The bond angles are set at 120 degrees .Three bonding pairs and zero lone pairs.
3.Tetrahedral-formed or found when there are four bonds all in one central atom , with no extra unshared electron pairs.
4.Octahedral-the bond angle is set at 90 degrees.Contains six pairs of electrons .
5. Pyramidal-have pyramid –like shapes.Requires three dimensions in order to fully separate the electrons.There are only three pairs of bonded electrons leaving one unshared lone pair.
6. Bent- Angular , have a non linear shape. 2 pairs of bonded electron and 2 unshared lone pairs.
• In Carbon dioxide , the carbon will be the central atom since it has the greater number of unpaired electron and the bond angle will be at 180 degree ,there will be two bonding pairs and zero lone pairs.So it is considered linear.
• In BF3,the Fluorine will be the central atom since it has the greater number of unpaired electrons.thre will be three bonding pairs and zero lone pair and it is considered Trigonal Planar.
• In SO2,it is considered bent because there will be two bonding pairs and one lone pair due to the presence of coordinate covalent bond which is a pair of electron supplied only by one of the two atoms and the sulfur will be the central atom since it has a lower electronegativity than oxygen and they have the same number of valence electrons and the oxygen will be the substituent atom –the atom which is bonded or connected to the central atom.so the position of the molecule will be angular and therefore it is considered bent.
• In CH4, the carbon will be the central atom and hydrogen will be the substituent atom and there will be four bonding pairs and zero lone pairs and therefore it is considered tetrahedral.
• In SF6, it is considered octahedral since it has six bonding pairs and zero lone pairs and the bond angle will be set at 90 degrees and the other is 180 degrees.
• In NH3, it has three bonding pairs and one lone pair making it to become trigonal pyramidal and the bond angle will be set at 107 degrees.
IMPORTANCE OF MOLECULAR GEOMETRY
ReplyDeleteThese are the reasons why geometry is important:It hones one's thinking ability by using logical reasoning., It helps develop skills in deductive thinking which is applied in all other fields of learning., Artists use their knowledge of geometry in creating their master pieces., It is a useful groundwork for learning other branches of Mathematics., Students with knowledge of Geometry will have sufficient skills abstracting from the external world., Geometry facilitates the solution of problems from other fields since its principles are applicable to other.
They also help determining macroscopic properties such as melting and boiling points. It also predicts the ways in which one molecule can react with another.
Clearly it is very important to know the shape of a molecule if one is to understand its reactions. It is also desirable to have a simple method to predict the geometries of compounds. For main group compounds, the VSEPR method is such a predictive tool and unsurpassed as a handy predictive method. It is a remarkably simple device that utilizes a simple set of electron accounting rules in order to predict the shape of, in particular, main group compounds. Organic molecules are treated just as successfully as inorganic molecules. The assumptions and simplifications required by the method as outlined here should not encroach too far into descriptions of bonding: it is enough that the shape of molecules are successfully predicted.
Application of the VSEPR method requires some simplifying assumptions about the nature of the bonding. Despite this, the correct geometry is nearly always predicted, and the exceptions are often rather special cases. In a complete analysis of the geometry of a molecule it would be necessary to consider such factors as nuclear-nuclear interactions, nuclear-electron interactions, and electron-electron interactions. In the VSEPR method outlined here it is assumed that the geometry of a molecule depends only upon electron-electron interactions.
Intermolecular force
ReplyDeleteis a weak force compared to intramolecular force. It is a force holding molecule together .
A force of attraction or repulsion which act between neighboring particles, also known as Vander Waals force after the name of a dutch scientist Johannes Diderick Vander Waals.
The importance of this force is that it is responsible for the change in phase of a molecule because all matter will be in gaseous phase if there`s no Intermolecular force. Responsible for the solubility of a molecule.
There are three types of intermolecular force:
London Dispersion Force-it exist in all molecules and mostly present in all non-polar molecule and considered as the weakest of all but is especially important .It is considered volatile meaning it easily evaporate.
Example: methane or CH4.
Dipole-Dipole Force – exist in polar molecules.Has a permanent dipole. Electrostatic interaction of permanent dipole in molecules.Substances whose molecules have a dipole moment have higher melting point or boiling point than those similar molecules mass.
Example: Cabon Dioxide or CO2
Hydrogen bond-this is the strongest bond five times stronger than regular dipole- dipole bonds.It is formed if a hydrogen on a molecule is bonded to a high electronegative atom in the second row only(nitrogen,oxygen and fluorine).
Example:Water or H2O
Intermolecular Forces
ReplyDeletethere are three types of intermolecular forces:
>LONDON DISPERSION FORCES
>DIPOLAR FORCES
>HYDROGEN BOND
Forces binding atoms in a molecule are due to chemical bonding. The energy required to break a bond is called the bond-energy. For example the average bond-energy for O-H bonds in water is 463 kJ/mol. On average, 463 kJ is required to break 6.023x1023 O-H bonds, or 926 kJ to convert 1.0 mole of water into 1.0 mol of O and 2.0 mol of H atoms. A space filling model of water molecule is shown here.
The forces holding molecules together are generally called intermolecular forces. The energy required to break molecules apart is much smaller than a typical bond-energy, but intermolecular forces play important roles in determining the properties of a substances. Intermolecular forces are particularly important in terms how molecules interact and form biological organisms or even life.
In addition,Intermolecular forces are fundamentally electrostatic interactions (although London dispersion forces have a magnetic component also). Applying the classical electrostatic description, we understand that the greater the forces of attraction between molecules, the more the energy of the system must be increased as molecules are separated from each other, as in a phase change such as vaporization.
Also,Intermolecular forces play a major roll in determining the physical and chemical properties of biomolecules. Intermolecular forces are central to the most critical processes of biochemistry such as protein conformation and enzyme activity or DNA base-pairing.
here are three examples:
1. soap and water: when soap mixes with water, the soap gets between the intermolecular forces of the water molecules and reduces the surface tension. since the surface tension is reduced, the soap+water mixture can more easily cover more of a surface
2. in DNA (Deoxyribonucleic Acid) there are two strands made of nucleotides. each nucleotide in a strand is held together by covalent bonds, but the two large strands are held together by hydrogen bonds, which is weaker than covalent bonds. this intramolecular knowledge can be used in PCR, which is a biological technique that denatures the double strands using only heat, no enzymes.
3. Honey and syrup are two products found in the kitchen and used for normal everyday use. they are both made up of simple sugars like sucrose. the sucrose is a carbohydrate, or polyhydroxylated aldehyde. in each sugar, there are hydroxyl groups, and between sugars these hydroxyl groups bond (hydrogen bond). there are SO many hydroxyl groups, that the bonds create a network of molecules. knowledge of both inter and intramolecular forces can be used in changing the viscosity of honey and/or syrup. by adding heat, the bonds can be broken, and then viscosity can be reduced.
ReplyDeleteWhat are intermolecular forces?
Intermolecular forces are defined as the set of attractive and repulsive forces that occur between the molecules as a result of the polarity of the molecules.
When two or more atoms are joined by chemical bonds they form a molecule, electrons travel up to the new molecule and are concentrated in the most electronegativity atom area, the electronegativity is defined as property that have the atoms or molecules to attract electrons. The concentration of electrons in a defined area of the molecule creates a negative charge, while the absence of electrons creates a positive charge.
Dipoles are molecules that have negative and positive charged areas due to the electronegativity and concentration of electrons in molecules.
Intermolecular forces depend on the temperature, an increase of the temperature produces a decrease of the intermolecular forces.
1. They are weaker than chemical bonds, order of 100 times lower
2. The bond distance is at the level of microns
3. Unions are not directed.
Chemical bond
ReplyDeleteA chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electrostatic force of attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction. The strength of chemical bonds varies considerably; there are "strong bonds" such as covalent or ionic bonds and "weak bonds" such as dipole–dipole interactions, the London dispersion force and hydrogen bonding.
Since opposite charges attract via a simple electromagnetic force, the negatively charged electrons that are orbiting the nucleus and the positively charged protons in the nucleus attract each other. An electron positioned between two nuclei will be attracted to both of them, and the nuclei will be attracted toward electrons in this position. This attraction constitutes the chemical bond. Due to the matter wave nature of electrons and their smaller mass, they must occupy a much larger amount of volume compared with the nuclei, and this volume occupied by the electrons keeps the atomic nuclei relatively far apart, as compared with the size of the nuclei themselves. This phenomenon limits the distance between nuclei and atoms in a bond.
POLARITY
ReplyDeletewater is a polar substance, made so by the intermolecular forces (called dipole-dipole forces) between positive and negative charged ends of molecules. water's polar nature is due also to its structure and uneven sharing of electrons. the oxygen atom pulls electrons away from the hydrogen so there is an unequal sharing of elections. think of this as a higher concentration of negative charge around the oxygen atoms. this uneven balance of charge makes the two hydrogen atoms "bend" away from the oxygen.
for a substance to be soluble in water it usually must be polar too (remember: like dissolves like). however, ionic compounds (like NaCl) also dissolve in water whereas non-polar things such as CO2 do not dissolve in water. if you've taken organic chemistry note also that anything over about 4 carbons is relatively insoluble and by about hexane (6 carbons) it is totally insoluble. note also that molecular branching affects solubility, so t-butyl will vary in solubility compared to n-butyl.
generally, molecules with H, OH, N, S will be polar whereas most things with lots of carbons or diatomic molecules (O2, for example) will be non-polar
London Dispersion Forces
ReplyDeleteThe London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction. London forces are the attractive forces that cause nonpolar substances to condense to liquids and to freeze into solids when the temperature is lowered sufficiently.
Because of the constant motion of the electrons, an atom or molecule can develop a temporary (instantaneous) dipole when its electrons are distributed unsymmetrically about the nucleus.
Molecular Size
Dispersion forces are present between all molecules, whether they are polar or nonpolar.
Larger and heavier atoms and molecules exhibit stronger dispersion forces than smaller and lighter ones.
In a larger atom or molecule, the valence electrons are, on average, farther from the nuclei than in a smaller atom or molecule. They are less tightly held and can more easily form temporary dipoles.
The ease with which the electron distribution around an atom or molecule can be distorted is called the polarizability.
London dispersion forces tend to be:
stronger between molecules that are easily polarized.
weaker between molecules that are not easily polarized.
Molecular Shape
The shapes of molecules also affect the magnitudes of dispersion forces between them.
At room temperature, neopentane (C5H12) is a gas whereas n-pentane (C5H12) is a liquid.
London dispersion forces between n-pentane molecules are stronger than those between neopentane molecules even though both molecules are nonpolar and have the same molecular weight.
The somewhat cylindrical shape of n-pentane molecules allows them to come in contact with each other more effectively than the somewhat spherical neopentane molecules.
Molecular geometry, the bond lengths and angles, are determined experimentally. butane.chem.uiuc.edu
ReplyDeleteThe term electron-pair geometry is the name of the geometry of the electron-pair/groups/domains on the central atom, whether they are bonding or non-bonding. intro.chem.okstate.edu
Hybrid orbitals are very useful in the explanation of molecular geometry and atomic bonding properties.
Molecular Geometry
Molecular geometry, the bond lengths and angles, are determined experimentally. Lewis structures can give us an approximate measure of molecular bonding. There is a simple procedure that allows us to predict overall geometry is the VSEPR, Valence Shell Electron Pair Repulsion. The concept is that valence shell electron pairs are involved in bonding, and that these electron pairs will keep as far away from each other, due to electron-electron repulsion.
When two groups try to get as far away from each other as possible, a linear shape is formed.
INTERMOLECULAR FORCES
ReplyDeleteIntroduction:
The physical properties of melting point, boiling point, vapor pressure, evaporation, viscosity, surface tension, and solubility are related to the strength of attractive forces between molecules. These attractive forces are called Intermolecular Forces. The amount of "stick togetherness" is important in the interpretation of the various properties listed above.
There are four types of intermolecular forces. Most of the intermolecular forces are identical to bonding between atoms in a single molecule. Intermolecular forces just extend the thinking to forces between molecules and follows the patterns already set by the bonding within molecules.
1. IONIC FORCES:
The forces holding ions together in ionic solids are electrostatic forces. Opposite charges attract each other. These are the strongest intermolecular forces. Ionic forces hold many ions in a crystal lattice structure. Review - Ionic Bonds
2. DIPOLE FORCES:
Polar covalent molecules are sometimes described as "dipoles", meaning that the molecule has two "poles". One end (pole) of the molecule has a partial positive charge while the other end has a partial negative charge. The molecules will orientate themselves so that the opposite charges attract principle operates effectively.
In the example on the left, hydrochloric acid is a polar molecule with the partial positive charge on the hydrogen and the partial negative charge on the chlorine. A network of partial + and - charges attract molecules to each other.
Review - Polar Bonds
3. HYDROGEN BONDING:
Link to more extensive discussion: Hydrogen Bonding
The hydrogen bond is really a special case of dipole forces. A hydrogen bond is the attractive force between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule. Usually the electronegative atom is oxygen, nitrogen, or fluorine.
In other words - The hydrogen on one molecule attached to O or N that is attracted to an O or N of a different molecule.
In the graphhic on the left, the hydrogen is partially positive and attracted to the partially negative charge on the oxygen or nitrogen. Because oxygen has two lone pairs, two different hydrogen bonds can be made to each oxygen.
This is a very specific bond as indicated. Some combinations which are not hydrogen bonds include: hydrogen to another hydrogen or hydrogen to a carbon.
4. INDUCED DIPOLE FORCES:
Forces between essentially non-polar molecules are the weakest of all intermolecular forces. "Temporary dipoles" are formed by the shifting of electron clouds within molecules. These temporary dipoles attract or repel the electron clouds of nearby non-polar molecules.
The temporary dipoles may exist for only a fraction of a second but a force of attraction also exist for that fraction of time. The strength of induced dipole forces depends on how easily electron clouds can be distorted. Large atoms or molecules with many electrons far removed from the nucleus are more easily distorted.
http://www.elmhurst.edu/~chm/vchembook/161Ahydrogenbond.html
HYDROGEN BONDING
ReplyDeleteIntroduction:
The hydrogen bond is really a special case of dipole forces. A hydrogen bond is the attractive force between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule. Usually the electronegative atom is oxygen, nitrogen, or fluorine, which has a partial negative charge. The hydrogen then has the partial positive charge.
To recognize the possibility of hydrogen bonding, examine the Lewis structure of the molecule. The electronegative atom must have one or more unshared electron pairs as in the case of oxygen and nitrogen, and has a negative partial charge. The hydrogen, which has a partial positive charge tries to find another atom of oxygen or nitrogen with excess electrons to share and is attracted to the partial negative charge. This forms the basis for the hydrogen bond.
In other words - The hydrogen on one molecule attached to O or N that is attracted to an O or N of a different molecule.
In the graphic on the left, the hydrogen is partially positive and attracted to the partially negative charge on the oxygen. Because oxygen has two lone pairs, two different hydrogen bonds can be made to each oxygen.
This is a very specific bond as indicated. Some combinations which are not hydrogen bonds include: hydrogen to another hydrogen or hydrogen to a carbon.
Link to animation of Hydrogen Bonding in Water - Northland Community and Technical College
Hydrogen bonding is usually stronger than normal dipole forces between molecules. Of course hydrogen bonding is not nearly as strong as normal covalent bonds within a molecule - it is only about 1/10 as strong. This is still strong enough to have many important ramifications on the properties of water.
IMPORTANCE OF MOLECULAR GEOMETRY
ReplyDeleteMolecular Geometry of a compound can be predicted based on the elements present, the coordination number and the orbital hybridization. The Molecular Geometry of the compound can be used to help make predictions about crystal structures, dipole moment, reactivity, bond lengths and angles. The Molecular Geometry can be used to determine specific symmetry elements present, which in turn can predict IR and Raman bending or stretching modes which can help verify, spectroscopically, the structure of the compound of interest. Molecular geometry can also help the scientist visualize reactions of interest, reaction pathways, products or means of improving on the reaction of interest. The Molecular Geometry of well characterized compounds can be utilized in the efforts to explore new analytical spectroscopic techniques.
A strong understanding of Molecular Geometry can significantly help the Chemist.
**MAE ANDREA LO
ReplyDeleteMolecular Geometry
Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It determines several properties of a substance including its reactivity, polarity, phase of matter, color, magnetism, and biological activity. The angles between bonds that an atom forms depend only weakly on the rest of molecule, i.e. they can be understood as approximately local and hence transferable properties.
Some common shapes of simple molecules include:
• Linear: In a linear model, atoms are connected in a straight line. The bond angles are set at 180°. A bond angle is very simply the geometric angle between two adjacent bonds. For example, carbon dioxide and nitric oxide have a linear molecular shape.
• Trigonal planar: Just from its name, it can easily be said that molecules with the trigonal planar shape are somewhat triangular and in one plane (flat). Consequently, the bond angles are set at 120°. An example of this is boron trifluoride.
• Bent: Bent or angular molecules have a non-linear shape. A good example is water, or H2O, which has an angle of about 105°. A water molecule has two pairs of bonded electrons and two unshared lone pairs.
• Tetrahedral: Tetra- signifies four, and -hedral relates to a face of a solid, so "tetrahedral" literally means "having four faces". This shape is found when there are four bonds all on one central atom, with no extra unshared electron pairs. In accordance with the VSEPR (valence-shell electron pair repulsion theory), the bond angles between the electron bonds are arccos(−1/3) = 109.47°. An example of a tetrahedral molecule is methane (CH4).
• Octahedral: Octa- signifies eight, and -hedral relates to a face of a solid, so "octahedral" literally means "having eight faces". The bond angle is 90 degrees. An example of an octahedral molecule is sulfur hexafluoride (SF6).
• Pyramidal: Pyramidal-shaped molecules have pyramid-like shapes. Unlike the linear and trigonal planar shapes but similar to the tetrahedral orientation, pyramidal shapes require three dimensions in order to fully separate the electrons. Here, there are only three pairs of bonded electrons, leaving one unshared lone pair. Lone pair – bond pair repulsions change the angle from the tetrahedral angle to a slightly lower value. An example is NH3 (ammonia).
Central Atom it is the one that has the greater number of unpaired electrons.
Substituent Atom are atoms that bonds with cent
*Mae Andrea Lo:
ReplyDeleteREFLECTION:
Chemistry is indeed important. Why?
Everything we do is chemistry. . Let's start from the moment we woke up. Brushing teeth in the morning, cooking food, eating and taking a bath. All of this uses Chemistry. The toothpaste you used the chemical change that happens when you cook, the digestion part when eating, and the water, soap and shampoo that you used in taking a bath.
In connection to the subject we conducted a community base on our barangay which is called “Chem. Connect”. Its purpose is to know, the science dealing with materials, their composition, and the changes, which they undergo. In this method I learned what Chemistry really means. In Chem. Connect we experience tie dying, hand sanitizer and making charcoal out of flour. Chemistry fits into our lives. It offers new chemical frontiers and tells us what benefits may flow from them. Chemistry contributes to our existence, our culture, and our quality of life. Chemistry is concerned with the changes we see around us, like the rusting of iron, growing of grass, burning of wood and many more. Without these changes or chemical reactions our Planet Earth would be lifeless. Chem. Connect also help us in gaining extra income and producing a well quality product. It plays a critical role in man’s attempt to feed the world population, to tap new sources of energy, to clothe and house humankind, to provide renewable substitutes for dwindling or scarce materials, to improve health and conquer disease, and to monitor and protect our environment. Nothing concerns humans more than questions about the nature of life and how to preserve it. Since all life processes are brought about by chemical changes, understanding chemical reactivity is a vital foundation for our ultimate understanding of life. Thus chemistry, along with biology, contributes to human knowledge in areas of universal philosophical significance.
*MA. AHLYSSA TOLENTINO
ReplyDeleteChem-connect is a way to promote chemistry to other people. The learnings we had in our chemistry subject and teacher provide us to be involved in our community. What we have experimented; we share it in other people. Understanding chemistry is easy and enjoyable for it deals with matter. All around us involves chemistry. Knowing chemistry, it is physical science that investigates the molecular reasons occurring in the natural phenomenon in our daily living. Everything happens in our daily life can be answered by the use of chemistry. The first CHEM-CONNECT PROJECT we had in our community is challenging for us for we are involved for other people. We had done several experiments promoting chemistry. We successfully done the tie-dying were the people enjoyed and appreciate the colorful designed that appear in the shirt. Many people participated during our task they were really listening and we can see that they were interested. Some elderly people were amazed on how we arrived in that quality product. After our expanations, they gave their own opinion.
They said that it was their first time to be involved in that such project. Over all we can say that it was successful by the complement we heard from them. The smile and their happiness are marked in their faces
* ANTHONY BOBIS:
ReplyDeleteReflection
Chemistry is fun because it is all about us! In our everyday lives,almost everything we use is made of materials produced through chemical processes.The work of chemists is for us- from toothpaste you use everyday to the most complex material you use. Chemistry is often referred to as the central science . . .you know why? Because it touches nearly every part of our lives . .and also it is essential to the diff. fields of science and other subjects. Biologist need to learn chemistry for them to understand the chem.processes taking place in the body. Also, industries used the principles of chemistry. So understanding chemistry is essential to our life. Beside from understanding the chemistry why don't we apply it in our every lives?don't you? Through the help of chem.connect we're be able to understand well the field of chemistry and be able to use it to our every lives and share it to our family,friends.
By JAN AIRISH BUENDIA
ReplyDeleteREFLECTION
(CHEM-CONNECT)
Chemistry is really helpful in our daily living…
What is chemistry?
Chemistry is a physical science that investigates the molecular process /reasons occurring in our macroscopic world. Everything is made up of chemistry. I’m really honored to be a part of this CHEM-CONNECT PROJECT Of course with the help of our chemistry teacher, Mr. Ronaldo Reyes for through this, I have gained more knowledge about chemistry, and not only that! I was able to share it to other people in a community. Promoting chemistry to the people in a community is enjoying, enjoying in the fact that I was given the opportunity to share my knowledge to them and to teach them some practical applications in chemistry. Examples of this practical applications we had promoted to a community are the making of charcoals, hand sanitizers , gel, and mango shake which can be an additional profit to some families.
Through CHEM-CONNECT I understand more about chemistry; its importance in our daily living, and how it affects the human life. This learnings I have gained will be really useful to me. And to make sure it will not be wasted I will share it to other people and make sure they will love chemistry like how I loved it too…
By JAN AIRISH BUENDIA
ReplyDeleteINTERMOLECULAR FORCE
>they are weak forces compared to intramolecular forces
> change in phase of molecules occur
> without it all matter would be in the gaseus phase
LONDON DISPERSION FORCES
>instantaneous-induced dipole
>small flactuation of electron clouds occur
>occurs on non polar molecules
DIPOLAR FORCES
> electrostatic interactions between permanent dipoles in molecules. These interactions tend to align the molecules to increase attraction (reducing potential energy).
HYDROGEN BOND
> the attraction between the lone pair of an electronegative atom and a hydrogen atom that is bonded to either nitrogen, oxygen, or fluorine.
COHESION
>tendency of similar or identical particles/surfaces to cling to one another
ADHESION
>the tendency of dissimilar particles or surfaces to cling to one another
SURFACE TENSION
>imbalance of forces in the surface of liquids
-Caroline Drew Macariola
ReplyDeleteWhy do atoms combine?
-Atoms combine to become stable-To achieve the noble gas configuration
Remember:*When an atom gives up, its charge becomes positive*When an atom accepts, its charge becomes negative
Chemical Bond is the attracting force existing between any two atoms. There are many types of chemical bond but the two most basic types are Ionic and Covalent Bond. Ionic is the transfer of electrons from metal to non-metal while covalent bond is the sharing of electrons in two or more non-metals.
Properties of Covalent Compound:
-Covalent compounds have lower melting and boiling point than ionic compounds because they are easy to separate unlike the ionic compounds.-Covalent compounds are soft and flexible because these molecules can move around each other easily beacuse there are no bonds between them.-Covalent compounds are flammable than ionic.They contain hydrogen and oxygen atoms that can react to form carbon dioxide and water with oxygen gas so it is more flammable.-Covalent compounds are poor conductor because we say that electricity is conducted in the water from the movements of the ion. There are no ions in the molecules so it cannot be a good conductor.
Properties of Ionic Compound:
-Ionic Compounds forms crystal because the ions tends to stack into forces between opposite ions but they are softer than ionic crystals-They have higher melting and boiling point because it takes a lot of energy for the crystals to get pulled apart from each other.-Ionic are hard and brittle because the positive and negative ion are strongly attached to each other, also because when you hit it, it feels hard cause of the crystals.
-Ionic compounds are good conductors if melted or in liquid form because when they are in liquid form the ions are free to conduct electricity, we say that electricity is conducted in water from movements of ions from one place to another so that's it but it isn't good if it is in solid form because of ionic bond.
Ex. Salt solid solution-poor conductor Salt liquid solution-good conductor
By the way, Lone pairs are unpaired atoms.
Example, H2O has 2 lone pairs
Caroline Drew Macariola
ReplyDeleteAnd also, Intramolecular force of attraction is the force of attraction that exist between bonds within a molecule.
Beryllium has 2 outer electrons because it is in group 2. It forms bonds to two chlorines, each of which adds another electron to the outer level of the beryllium. There is no ionic charge to worry about, so there are 4 electrons altogether - 2 pairs.
It is forming 2 bonds so there are no lone pairs. The two bonding pairs arrange themselves at 180° to each other, because that's as far apart as they can get. The molecule is described as being linear.
Three electron pairs around the central atom
The simple cases of this would be BF3 or BCl3.
Boron is in group 3, so starts off with 3 electrons. It is forming 3 bonds, adding another 3 electrons. There is no charge, so the total is 6 electrons - in 3 pairs.
Because it is forming 3 bonds there can be no lone pairs. The 3 pairs arrange themselves as far apart as possible. They all lie in one plane at 120° to each other. The arrangement is called trigonal planar.
Four electron pairs around the central atom
There are lots of examples of this. The simplest is methane, CH4.
Note: Elsewhere on the site, you will find the shape of methane worked out in detail using modern bonding theory. Here we are doing it the quick and easy way!
If you are interested in the bonding in methane you can find it in the organic section by following this link, or in a page on covalent bonding by following this one.
Carbon is in group 4, and so has 4 outer electrons. It is forming 4 bonds to hydrogens, adding another 4 electrons - 8 altogether, in 4 pairs. Because it is forming 4 bonds, these must all be bonding pairs.
Four electron pairs arrange themselves in space in what is called a tetrahedral arrangement. A tetrahedron is a regular triangularly-based pyramid. The carbon atom would be at the centre and the hydrogens at the four corners. All the bond angles are 109.5°.
Five electron pairs around the central atom
A simple example: phosphorus(V) fluoride, PF5
(The argument for phosphorus(V) chloride, PCl5, would be identical.
Phosphorus (in group 5) contributes 5 electrons, and the five fluorines 5 more, giving 10 electrons in 5 pairs around the central atom. Since the phosphorus is forming five bonds, there can't be any lone pairs.
The 5 electron pairs take up a shape described as a trigonal bipyramid - three of the fluorines are in a plane at 120° to each other; the other two are at right angles to this plane. The trigonal bipyramid therefore has two different bond angles - 120° and 90°.
Six electron pairs around the central atom
A simple example: SF6
6 electrons in the outer level of the sulphur, plus 1 each from the six fluorines, makes a total of 12 - in 6 pairs. Because the sulphur is forming 6 bonds, these are all bond pairs. They arrange themselves entirely at 90°, in a shape described as octahedral.
Two slightly more difficult examples
Xenon forms a range of compounds, mainly with fluorine or oxygen, and this is a typical one. Xenon has 8 outer electrons, plus 1 from each fluorine - making 12 altogether, in 6 pairs. There will be 4 bonding pairs (because of the four fluorines) and 2 lone pairs.
There are two possible structures, but in one of them the lone pairs would be at 90°. Instead, they go opposite each other. XeF4 is described as square planar.
Each lone pair is at 90° to 2 bond pairs - the ones above and below the plane. That makes a total of 4 lone pair-bond pair repulsions - compared with 6 of these relatively strong repulsions in the last structure. The other fluorine (the one in the plane) is 120° away, and feels negligible repulsion from the lone pairs
(*) Chemical Bonding (*)
ReplyDelete“Intramolecular force”
- A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. Atoms combine to become stable-to achieve the noble gas configuration. When an atom gives up, it charge becomes positive. When an atom accepts, its charge become negative.
2 types
IONIC BOND- transfer of electrons (e-) from metal to non-metal.
COVALENT BOND- sharing of electrons (e-) for non-metals.
REFLECTION:
Sharing knowledge about chemistry is one way that we students can do.
In able to share our knowledge, we have the Chem-connect project headed by our chemistry teacher Mr. Ronaldo Reyes. Our objective in this project is to share the importance and the practical application of chemistry in our daily life. This project is presented by Tabaco National High School (TNHS) students especially the III-Hydrogen class. Our class is divided into some groups and chosen their community.
Chemistry is all around us. Especially chemistry products. Everything that you see, touch, and taste is chemistry and chemistry products. In our own home, we can find this. To understand more, chemistry is the one we use in our daily life. For example, in cooking. Salt and sugar is very important to enhance the flavor of our dishes. These products are composed of different elements and compounds. The salt is (NaCl) and sugar is (C12H22O11). For our personal kits or hygiene, we use lotion to soften and to hydrate our skin. Those lotions that we use are also composed of different elements and compounds.
PRACTICAL APPLICATION:
We have this practical application in our project. In chemical bonding the perfect product to be made is "tie dyeing or tie dye."
You can also make toothpaste, nontoxic clay, our favorite deserts like shakes that we also made in our project. We can make it in our own home and we are sure that it is clean and safe and it is affordable. After making that by your own, you can share it to your family and also to your community.
*INTERMOLECULAR FORCES- weak force
ReplyDelete-also known VAN DER WAALS FORCES
*INTERMOLECULAR FORCES occur between molecules
*INTRAMOLECULAR FORCES occur between atoms
1. London Dispersion Forces- lowest boiling point
-exist in all molecules, but are especially important in non polar covalent molecules
-electron is temporary
-forces are weakest
2. Dipolar Forces- stronger than LDF
-electrons are permanent
3. H-Bond-about five times stronger than regular dipole-dipole bond
-strongest
-usually bond to N, O, F
- Hydrogen atoms bonded to highly electro negativity
*INSTANTANEOUS-INDUCED DIPOLE-small fluctuation of electron clouds
*VOLATILE SUBSTANCES- easily evaporate
-lowest boiling point
*As the MOLAR MASS increases the BOILING POINT also increases.
*PHASE CHANGES- weak forces/bonds are broken
*INTERMOLECULAR FORCES- usually cohesive forces
*GASSEOUS PHASE- state without inter molecular forces
*COHESION- similar particles
*ADHESION- dissimilar particles
*HIGHER BONDING- LOWEST VOLATILE
*Consider the BOILING POINT- when its the same IMF
Alizza May Salando
10/29, 8:04am
Alizza May Salando
*CHEMICAL BOND- A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms.
*IONIC- metal + non metal
*COVALENT- non metal + non metal
1. Polar – involves unequal sharing of elections
2. Non polar- involves equal sharing of electrons
*ELECTRONEGATIVITY- if the electro negativity difference is equal to zero, non polar
*POLAR - 0.1 to 1.6
*IONIC - 1.7 up
*DIPOLE- partial positive, partial negative charge in same direction
*POSITIVE DIPOLE- lower electro negativity
*NEGATIVE DIPOLE- higher electro negativity
*EXCEPTIONS:
• Incomplete octet
• Expanded octet
• Odd no. of electron
*HYDRO CARBON- substances containing carbon and hydrogen are all non polar (methane)
*SYMMETRICAL SHAPE- bases of being non polar
*LIKE DISSOLVES LIKE- Polar dissolves polar
Non polar dissolves non polar
*Candle- non polar
*Water- polar
*Oil- non polar
PHYSICAL AND CHEMICAL CHANGE
ReplyDeletePhysical change is a change in which the substance changes form but keeps its same chemical composition (reversible).
EXAMPLE:
*Changes of state are considered to be physical changes
-melting
-freezing
-evaporating
*If you fold a piece of paper it is a physical change because it changes only on its size
*If you heat an iron bar until it glows red hot, it is still chemically the same iron. The iron has not changed into something else.
*dissolving sugar on water is also physical
@ No new substance is created during a physical change, although the matter takes a different form. The size, shape, and color of matter may change.
---CHEMICAL change----
A chemical change is a change in which something new is formed (irreversible).
example:
*combustion
-it always have a product of carbon dioxide and water
*rusting of nail/iron
*digesting or metabolism of food
however,there are indicators that says that there a chemical reaction
-formation of precipitation
(insoluble jelatinous substance)
-formation of bubbles
-change in color
-change in odor
-evolution of heat and gas
-change in temperature
-evolution of gas
-production of electrical energy
(battery of a car and flashlight)
-production of mechanical energy
(explosion of dynamite)
but there are substance that undergo both physical and chemical change
*CANDLE
*burning of candle is chemical change
*melting of candle is physical change....
thank you sir reyes,we really appreciate your lesson to cause it really help us in our daily living....
Physical Change - when a substance undergo the process, we can change it to its original phase.
ReplyDelete* Phase change is a physical change ( sublimation, boiling etc.. )
Chemical Change - we can not change it to its original phase
Indicators:
1. production of electrical energy *ex. light used*
2. formation of bubbles
3. emitition of foul odor
4, change in temperature
5. change in color
6. production of mechanical energy *ex. explosion of dynamite*
7. evolution of gas
SHEENA ECHAGEN
ReplyDelete* Chem-connect help us understand more ideas about Chemistry.
Physical and Chemical Change is something to do with our surroundings. Without noticing things might undergo changes like physical change that change its physical structure but doesn't change into new substance while chemical change is a change that forms new substance like cooking. We notice that after cooking we can't turn it to its original form into raw substance.
* This can be applied to things around us like cooking, drying fish, making abaca bags, and so many more that we need to our daily life.
*This can help our community to understand these changes and what advantages it can do for us. Some of it can be useful to us. For example water that undergoes physical change when evaporates but it turns into its original form to became water.
- Another drying fish
.. Where in dying there's physical change that the fish dries but it still a fish.
CHEMICAL REACTION is change in which new substance is formed(irrevesible)
ReplyDeletehowever,there are 4 types of chemical reaction......
The Four Major Types of Reactions
(1) combination or synthesis reactions
= Two or more reactants unite to form a single product.
*General Reaction Pattern = A + B ----> AB
example:SULFUR + OXYGEN=SO2
(2) decomposition reactions
= A single reactant is decomposed or broken down into two or more products.
* General Reaction Pattern = AB ----> A + B
EXAMPLE: CaCO3=CaO+CO2
(3) substitution or single replacement reactions
= A single free element replaces or is substituted for one of the elements in a compound. The free element is more reactive than the one its replaces.
*General Reaction Pattern = A + BC ----> B + AC
EXAMPLE: Zn + 2HCI =H2 +ZnCI2
(4) metathesis or double displacement reactions
This reaction type can be viewed as an "exchange of partners." For ionic compounds, the positive ion in the first compound combines with the negative ion in the second compound, and the positive ion in the second compound combines with the negative ion in the first compound.
* General Reaction Pattern = AB + CD ----> AD + CB
EXAMPLE: HCI + NaOH = NaCI + HOH
These are the four types of chemical reaction.........thank you...,
PHYSICAL AND CHEMICAL CHANGE
ReplyDeletePhysical Change- doesn't require to change the chemical composition of a certain substance
- it has only a weak bond
- rearranges molecules but don't affect their internal structures
Some examples are :
> whipping egg
> dicing potatoes
> drying of clothes
> dissolving sugar in water
( phase changes are also physical changes because they can be brought back to its original form )
Chemical Change- defined as the change of the chemical composition of a matter
- any change that results in the formation of new substances.
- involves making or breaking bonds between atoms
- has a strong bond
Examples are :
> iron rusting (iron oxide forms)
> milk souring (lactic acid is produced)
> gasoline burning (water vapor and CO2 is formed)
> suntanning (melanin is produced)
INDICATORS OF CHEMICAL CHANGE
* color changes
* temperature changes
* formation of precipitate
* production of bubbles
* evolution of gas
* odor released
FORMAL CHARGE- a charge assigned to an atom in a given formula
Formula in getting the FC.
FC= no. of valence electron - (no.of unshared electron + half no. of shared electron)
resonance- substance with two or more acceptable structure
FACTORS AFFECTING THE RATE OF CHEMICAL REACTION
ReplyDeleteDuring the chemical reaction there is also a factors that is happening....
Like the collision,
when there is collision, there is pressure that is produce
these collision or colliding of particles breaks down the bond in the molecule
Factors that Affect the Chemical Reaction
1.CONCENTRATION
=EXAMPLE:
A B C
30 ml vinegar 20 ml vinegar 5 ml vinegar
10 ml water 25 ml water
=in observation container A produces more bubbles.....container B is lesser bubbles than A
and container C has least bubbles produced......
DILUTION-lowering the concentration by adding more solvent
*in concentration,the higher the concentration the faster the rate of chemical reaction
*the presence of more particles is more collision happen(frequent collision)..
2.TEMPERATURE
A B C
Hot cold tap
=in observation,more bubbles is produce in A,lesser in B,least in C
*in temp.,the higher the temp. the faster the chemical reaction
*there is more kinetic energy
3.SURFACE AREA
A B
crushed antacide whole
(faster) (lesser)
*the greater the surface area,the faster the rate of chem. reation is
*more collision happen
4.CATALYST
*ANY SUBSTANCE that speeds up the chem. reaction without being consumed by itself
*example
@papain-catalyst contain by papaya
*lowers the activation energy of reaction
5.INHIBITOR
*is subs. that slows down the chem. reaction
*increases the activation energy
*oxidation
*called the negative catalyst................
by grizel gomez
ReplyDeletePhysical change is a change in which the substance changes form but keeps its same chemical composition (reversible).
*Changes of state are considered to be physical changes. Liquid water and ice (frozen water) are both the same substance, water.
*If you fold a piece of paper it is a physical change. You have changed the form of the paper but you have not changed the fact that it is paper.
*If you heat an iron bar until it glows red hot, it is still chemically the same iron. The iron has not changed into something else.
*If you dissolve salt in water you have not changed the materials chemically. You still have salt and you still have water. This can be shown if you choose to separate the mixture by distillation or the simple evaporation of the water. The salt would be the residue and the water would be the distillate.
A chemical change is a change in which something new is formed (irreversible). The starting materials change into an entirely different substance or substances. This new substance has a different chemical composition than the starting materials. Examples of chemical changes would be the reaction of iron with air (rusting} or the reaction of a metal and acid.
Certain observations will indicate that a chemical change has occurred.
*The reaction produced a change in temperature. The temperature could go up (gets hotter) or the temperature could go down (gets colder). Note: reactions that produce heat are known as exothermic reactions whereas reactions that absorb heat are known as endothermic reactions.
*Formation of gas bubbles.
*Formation of a solid (precipitate).
*A change in color. You may start with two colorless solutions but when they are mixed you might see a bright purple color.
*Formation of a different odor. The starting materials may not smell at all but as you mix these materials you may end up with a bad odor or a pleasant one.
How to Tell Chemical & Physical Changes Apart?
A chemical change makes a substance that wasn't there before. There may be clues that a chemical reaction took place, such as light, heat, color change, gas production, odor, or sound. The starting and ending materials of a physical change are the same, even though they may look different.
Are you confused about the difference between chemical changes and physical changes and how to tell them apart? In a nutshell, a chemical change produces a new substance, while a physical change does not. A material may change shapes or forms while undergoing a physical change, but no chemical reactions occur and no new compounds are produced.
In some cases, it may be hard to tell whether a chemical or physical change occurred. For example, when you dissolve sugar in water, a physical change occurs. The form of the sugar changes, but it remains the same chemically (sucrose molecules). However, when you dissolve salt in water the salt dissociates into its ions (from NaCl into Na+and Cl-) so a chemical change occurs. In both cases a white solid dissolves into a clear liquid and in both cases you can recover the starting material by removing the water, yet the processes are not the same.
The difference between a physical reaction and a chemical reaction is composition. In a chemical reaction, there is a change in the composition of the substances in question; in a physical change there is a difference in the appearance, smell, or simple display of a sample of matter without a change in composition. Although we call them physical "reactions," no reaction is actually occurring. In order for a reaction to take place, there must be a change in the elemental composition of the substance in question. Thus, we shall simply refer to physical "reactions" as physical changes from now on.
Examples of Chemical Changes
ReplyDelete• burning wood
• dissolving salt in water
• mixing acid and base
• digesting food
Examples of Physical Changes
• crumpling a sheet of paper
• melting an ice cube
• casting silver in a mold
• breaking a bottle
Change of State
The change of state is likewise a physical change. In this scenario, one can observe a number of physical properties changing, such as viscosity and shape. As ice turns into water, it doesn't retain a solid shape and now becomes a viscous fluid.
The physical "reaction" for the change of ice into liquid water is:
H2O (s) → H2O (l)
Ice Melting
The following are the changes of state:
Solid→Liquid Melting
Liquid→Gas Vaporization
Liquid→Solid Freezing
Gas→Liquid Condensation
Solid→Gas Sublimation
If heat is added to a substance, such as in melting, vaporization, and sublimation, the process is endothermic. In this instance, heat is increasing the speed of the molecules causing them move faster.
If heat is removed from a substance, such as in freezing and condensation, then process is exothermic. In this instance, heat is decreasing the speed of the molecules causing them move slower.
Indicators of chemical change:
Change in Temperature
A change in temperature is characteristic of a chemical change. During an experiment, one could dip a thermometer into a beaker or Erlenmeyer Flask to verify a temperature change. If temperature increases, as it does in most reactions, a chemical change is likely to be occurring. This is different from the physical temperature change. During a physical temperature change, one substance, such as water is being heated. However, in this case, one compound is mixed in with another, and these reactants produce a product. When the reactants are mixed, the temperature change caused by the reaction is an indicator of a chemical change.
Violent Reaction (Fireworks) that has Heat as a Product
Reaction: Fe2O3 + 2Al → 2Fe + Al2O3 + Heat
Change in Color
A change in color is also another characteristic of a chemical reaction taking place. For example, if one were to observe the rusting of metal over time, one would realized that the metal has changed color and turned orange. This change in color is evidence of a chemical reaction. However, one must be careful; sometimes a change in color is simply the mixing of two colors, but no real change in the composition of the substances in question.
Metal Rusting
The reaction above is that of the rusting of iron.
Reaction: 4Fe + 3O2 + 6H2O → 4Fe(OH)3
Emission of Odor
When two or more compounds or elements are mixed and a scent or odor is present, a chemical reaction has taken place. For example, when an egg begins to smell, (a rotten egg) a chemical reaction has taken place. This is the result of a chemical decomposition.
Spoiled Egg
Formation of a Precipitate
The formation of a precipitate may be one of the most common signs of a chemical reaction taking place. A precipitate is defined to be a solid that forms inside of a solution or another solid. Precipitates should not be confused with suspensions, which are solutions that are homogeneous fluids with particles floating about in them. For instance, when a soluble carbonate reacts with Barium, a Barium Carbonate precipitate can be observed.
Test Tube
Reaction: Ba2+(aq) + CO32-(aq) → BaCO3(s)
Formation of Bubbles
The formation of bubbles, or rather a gas, is another indicator of a chemical reaction taking place. When bubbles form, a temperature change could also be taking place. Temperature change and formation of bubbles often occur together. For example, in the following image, one can see a gas spewing. This is the formation of a gas.
Gas Formation
However, most reactions are much more subtle. For instance, if the following reaction occurs, one may notice Carbon Dioxide bubbles forming. If there is enough Hydrochloric Acid, bubbles are visible. If there isn't, one can't readily notice the change.
Reaction: Na2CO3 + 2HCl → 2NaCl + H2O + CO2
by grizel gomes
Delete*PHYSICAL CHANGE*
ReplyDeletePhysical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds.
Physical changes occur when objects or substances undergo a change that does not change their chemical composition.
Examples:
~chopping a wood
~crushing a can
~crumpled paper
*CHEMICAL CHANGE*
Chemical changes occur when a substance combines with another to form a new substance, called synthesis or, alternatively, decomposes into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions.
Examples:
~rusting of iron
~combustion of wood
Indicators of a Chemical Change
1.change in color
2.formation of solid compound or PRECIPITATE
3.emission of odor or smell
4.formation of bubbles
5.change in temperature
6.evolution of heat and light [burning of candle]
7.production of electrical energy [explosion of a dynamite]
8.production of mechanical energy battery in a car]
ANTHONY BOBIS
ReplyDeleteI learned that there are some
factors that affects the Chemical reactions of diff. Substances. . . .
MAJOR:
Concentration of reactants
it is because the higher the concentration the faster the rate of reaction is.
When a substance is concentrated there is the presence of more particles , so collision will take place . .and collision speeds up the reaction
Temperature
The higher the temp. The faster the reaction is . . ,because when a substance have a high temp. It possess high kinetic energy so it will result to collision of particles
Surface Area
the greater the surface area the faster the rate of reaction . .because the particles here are scattered so it can easily react with oxygen in the air which increases the rate of reaction
Presence of Catalyst
a substance that speeds up chem.reactiont
lowers the activation energy
ex. Papain (papaya)
Inhibitor
negative catalyst
slows down chem reaction
highers the activation energy
*SOME FACTORs THAT (AFFECT) HNDI with "s"
.
.
.
.
Minor
Pressure
concentration of gasses
Nature of reactants
Ionic compounds react faster than covalent
the physical change
ReplyDeleteIt is known that physical change means a change in the physical appearance or composition of a substance.In a physical change, there is just a change of state occurs. The new substance has the similar properties as the old substance. No new substances are formed. A physical change also involves changing the shape of the substance.
In a chemical change one or more new substances are created. The new substance is quite different from the original substance. It has the properties that are entirely different than those of the starting materials. In addition, we can’t able to get the original materials back easily.
So,we should understand its importance in human life.To be able to determine whether a substance is undergoing a physical or chemical change.Mostly of it are easily to reveres.
CHEMICAL CHANGE
ReplyDeleteA change in matter where new kinds of molecules with new properties are formed is called a
chemical change. Many chemical changes happen when you bring two or more different
substances together and are very difficult to reverse.
The basic framework of this topic centers on matter, how it’s defined, how it’s identified and how it’s classified. Students have learned that matter is anything that has mass and takes up space and that the physical world can be divided into matter and energy (the ability to do work). Because there are interactions among matter and energy, there will be change. Matter can change in two ways. A chemical change can happen or a physical change can happen. In a physical change, the appearance or form of the matter changes, but the kind of matter in the substance does not. In a chemical change, the kind of matter changes, and at least one new substance with new properties is formed. How and why these changes occur can be answered if we know its importance and the function.
For each chemical change, a chemical equation can be written that shows what the original
substance, or substances, are ultimately changed to.The starting materials, called reactants,
undergo a chemical change and produce the products.
Best examples are:
Examples:
1. Water can be divided into two substances: hydrogen and
oxygen using electricity in the process called hydrolysis.
Water is a liquid which puts out fire. Hydrogen and oxygen
are gases which can burn. The properties have changed, so
this is a chemical change.
Water Æ oxygen + water
Fig. 3: Hydrolysis of Water
2. When iron rusts, oxygen in the air is combining with the iron. A shiny, bendy gray metal turns
into a reddish brown powdery substance which is crumbly. A new substance has formed and a
chemical reaction has happened.
Iron + oxygen Æ iron oxide (rust)
3. Another example of a reaction is fire, or combustion. Paper is tough, crisp, and solid. When
the paper is done burning all that is left is some crumbly gray-black ashes and some gas in the
air which will not burn. The chemical reaction between the paper and the oxygen in the air
produced two new substances with different properties.
Paper + oxygen Æ carbon dioxide + ash
4. cooking of the raw food : in this process the raw food will chang to the cooked food and after cooking, the food doesn't have the same quality before cooking.
5. digestion of food: your body can't use the foods before digestion. digestion makes the to very small parts and molecules in order that your body can use the food.
6. burning of wood in fireplace: when the wood is burning, it will transform to ash and its not wood anymore, so its a chemical change.
7. Rusting of iron:When it is raining a lot or there is water in somewhere in you home, for example your bathroom, the irons in the house structure become rusted and they won't have the qualities that iron has, because it had an reaction with oxygen.
How can you tell that a chemical change has occurred and not a physical one?
First one must observe the physical properties of the reactants, and then considering the
physical properties of the products. If a chemical change has truly taken place, some or all the
physical properties of the products are different from those of the reactantsWe
must be careful since they all suggest that a new substance has been produced but any one of
them could also occur during a physical change. We therefore must observe several of the
following clues to be able to determine that a chemical change has occurred.
INDICATORS OF CHEMICAL CHANGE
ReplyDelete-Change of odor
-Change of color (for example, silver to reddish-brown when iron rusts).
-Change in temperature or energy, such as the production (exothermic) or loss (endothermic) of heat.
-Change of form (for example, burning paper).
-Light, heat, or sound is given off.
-Formation of gases, often appearing as bubbles.
-Formation of precipitate (insoluble particles).
-The decomposition of organic matter (for example, rotting food).
-production of mechanical energy
-production of electrical energy
-formation of bubbles
A chemical change can have a huge impact on a physical change.
Everyday Chemical Changes:
Humans are very good at utilizing the knowledge gained through various chemical changes.
For example it is known that when baking soda is heated carbon dioxide is produced. We used
this knowledge in baking, as the carbon dioxide bubbles cause the baked goods to rise.
Several chemical changes that are very important in our daily lives are combustion and
corrosion.
THE FACTORS THAT AFFECT THE CHEMICAL REACTION OF DIFF. SUBS. which i have learned in the class:
ReplyDelete...Concentration of reactants
- the higher the concentration the faster the rate of reaction is.
When a substance is concentrated there is the presence of more particles , so frequent collision will take place and collision speeds up the reaction
-measure of relative proportions of solute and solvent in a substance.
...Temperature
-The higher the temp. The faster the reaction is . . ,because when its higher,the particles move randomly in all direction and they collide.There is a high kinetic energy so there is the possibility to have a frequent collision and it speeds up the chemical reaction.
...Surface Area
-the greater the surface area the faster the rate of reaction . .because the particles here can scatter anywhere and they collide with each other, so it can easily react with oxygen in the air which increases the rate of reaction
...Presence of Catalyst
-a substance that speeds up chem.reaction without consuming itself.It mostly occur on decomposition reaction.
-it lowers the activation energy
ex. Papain (papaya)
-if put in tenola,it speeds up the reaction because it lowers the activation energy.
...Inhibitor
-negative catalyst
-it slows down chem reaction
-it inreases the activation energy
example:apple
-it turns into brown when expose in air brcause subs. in apple reacrs with air.
ANTHONY BOBIS
ReplyDeleteThere are several possible chemical reactions that take place in the human body and in our enviroment.For example,our family doctor prescribes a specific drug to cure our illness when we're sick.This predicament is possible because diff.chem.compounds may produce diff.chem.reactions in our body.
There are many ways to categorize chem.reactions.Not all chem.reactions,however ,fit exactly into one of these classes.Sometimes,a reaction may fit equally well into two of these categories.Recognizing a chem.reaction as a particular type is useful.It would be highly meaningful for you to determine the classification of chem.reactions in order to predict the products of these reactions.
These are the main kinds of chem.reaction
Combination Reaction/synthesis/direct combination
-it takes place when 2/more elements/ between a compound and element combine to form a more complex compound.
-gen.equation: A+B=AB
-ex. Cu+S=CuS
Decomposition/Analysis Reaction
-one substance usually a compound ,breaks down into 2/more elements or compound
-gen.equation
AB----->A+B
-it this reaction heat is usually applied
-ex. H2O--->H2+ O
Single Replacement/Substitution
-one element reacts by replacing another element in a compound
-gen.equation
A+BC=AC+B
-ex.Mg+2HCl=MgCl2+H2
Double Replacement/ Metathesis
-exchange of ions by 2 compound/reactants to form 2 diff.products
-gen.equation
AB+CD=AD+CB
-ex. Neutralization
REFLECTION
ReplyDeleteIn our simple but very important environment which we live in occur different changes happen that we do not simply known and cannot be seen by our naked eye yet cannot be simply identified by our ordinary knowledge but needed experiment and proof to accept this changes.
In chemistry,there are two changes that are classified.These are physical and chemical change......
as i learned,physical change is a change in which a subs. undergo in changes but its chemical composition remains the same.What do we mean by this?example,a broken glass you will observe that the glass is broken into pieces but it is still a glass.Change in phase in matter is also physical change ;evaporation,melting,freezing and other....as i learned Chemical Change is a change in which a new subs. is formed..Like burning of wood,when we cook using wood some do not know that we apply chemical change.why? because when we burn a wood an ASH is formed.But how do we know that we undergo chem. reaction,there are indicator that a chem. reaction occur;formation of heat/light,bubbles,precipitate,change in odor/color are the common indicator that you will observe
others are;production of mechanical energy in explosion of dynamite,production of elec.energy in battery of car and flashlight,evolution of gas and temp. change..............
these are only one of many changes happen in our environment.We don not even known them,but we need to know it.these will help us in our daily life.Like preventing harmful reaction that can cause harmful effect in our body....ALL OF THIS CHANGES,I LEARNED IN CHEMISTRY..........
Chemical Reaction is a short hand method on representing a chemical reaction using chem. formula.
ReplyDeleteI’d learned that there are 4 types of chemical reaction such as – Combination , Decomposition, Single Replacement and Double Displacement.
Combination – two or more reactions unite to form a single reactant ( A+B AB )
Decomposition – a single reactant is decomposed or broken down into or more similar simple substance ( AB A+B )
Single Replacement – one reactant and one compound ( A + BC B + AC )
Double Displacement – two compounds and two reactants ( AB + CD AD + CB )
- salt and water
I also learned that in balancing CR we need to put coefficients beside the symbol of the element or compound ( smallest possible whole number ). When balancing, don’t remove or change the subscript.
There are applications that can help us in our daily lives. I learned the diff. mixtures that shouldn’t be mix together because it can affect us. Those mixed substances can produce toxic gas that will affect our health and environment.
The lesson discussed can now help me classify which substances shouldn’t be mixed together.
*TYPES OF CHEMICAL REACTION*
ReplyDelete>Combination Reaction
~2 or more reactants unite to form a single product
~A+B→AB
>Decomposition
~the single reactant is decomposed or broken down into 2 or more substances decomposes
~AB→A+B
>Single Replacement
~a single-free element replaces or is substituted for one of the elements in a compound
~A+BC→B+AC
>Double Displacement
~This reaction type can be viewed as an "exchange of partners." For ionic compounds, the positive ion in the first compound combines with the negative ion in the second compound, and the positive ion in the second compound combines with the negative ion in the first compound.
~AB+CD=AD+AC
*MOLE*
ReplyDelete~Mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as the amount of any substance that contains as many elementary entities as there are atoms in 12 grams of pure carbon-12 (12C), the isotope of carbon with relative atomic mass 12. This corresponds to the Avogadro constant, which has a value of 6.02214129(27)×1023 elementary entities of the substance. It is one of the base units in the International System of Units, and has the unit symbol mol and corresponds with the dimension symbol N. In honour of the unit, some chemists celebrate October 23 (a reference to the 1023 part of Avogadro's number) as "Mole Day".
>>6.02 × 10(23)
~atom-elements
~ions-charged
~molecule-covalent/molecular compound
~formula unit or ion pair-ionic substances
-1 mole Na=6.02×10(23)Na atoms
-1 mole H2O=6.02×10(23)H2Omolecules
-1 mole NaCl=6.02×10(23)ion pair
-1 mole Cl=6.02×10(23) ions
-2 molesH2O=1.204×10(24)H2O molecule
*FACTORS AFFECTING THE RATE OF CHEMICAL REACTION*
ReplyDelete-reactant particles must collide with each other to form pressure
-COLLISIONS must be of enough energy to overcome the the "energy barrier" called the ACTIVATION energy(minimum energy needed to start a chemical reaction
-reactants must form a new bonds to produce products
>Concentration
~the higher the concentration,the faster the reaction
~if there are more particles,there is a tendency of collision of particles which speed up the chemical reaction
>Temperature
~the higher the temperature,the faster the reaction
~it possesses higher kinetic energy
~collision is frequent
>Surface Area
~the greater the surface area,the faster the rate of reaction
~WHY??? the particles are scattered so they can collide with other particles or molecules.
>Catalyst
~Substance that speeds up a chemical reaction without consuming itself in a chemical reaction
~Lowers the activation energy
~CATALASE-H2O+O2
>Inhibitor
~increases the activation energy
~slow chemical reaction
CAROLINE DREW MACARIOLA
ReplyDeleteChemical Reaction
Ammonia+Bleach=Chloramin
-Never dare mixing this,it will cause a very toxic gas hazardous)
-Chestpain,shortness of breating
-irritation,lung injury, pneunomia
-watery eyes
Bleach+Acid=chlorine gas
-irritates membrae
-inflamation
Chlorine gas+water= Hydrrochloric acid and Hypochlorous acid
-burns skin,runny nose,chestpain, pneumonia,death
Precautions:
-Do not dipose anywhere, it will cause spontaneous combustion
-If splattered,flush with water
-proper ventalation
-wear protective clothing
-Sodium hydroxide ~water is less dense with sulfuric acid
In mixing: Acid to water
Base to water
~if reversed it will cause exothermic reaction
-be cautious with paint remover it is flammable
-orthodormat spray+acid type chemical=highly flammable gas
When buying:
-least toxic and eco-friendly
-avoid cleaning products that contains chlorine
-no smoking
-follow the directions
-no lenses when usig
-proper ventalations
Factors Affecting the Rate of a Chemical Reaction
1) The reactants particles must collide with each other
-Pressure is created
2)Te collisions must be of enough energy to overcome the energy barier,called the activation energy
-Activation energy is the minimun energy needed to start a chemical reaction. This is why these things do not happen, there is an energy barier so most reactions need to be started off by putting on some energy.
3)The reactants must form new bonds to produce products
-when bonds are broken, new substance are produced
Factors Affecting te rate of reaction
1)Concentration
-dilution-lowering the concentration of substance by adding more water
-the higher the concentration the fster the reaction because if a solution is concentrated there is a presence of more particles which causes collision and when it is frequent,thechemical reaction will speed up
2)Temperature
-the higher the temperature the faster the reaction because they posses higher kinetic energy so the collision is frequent and when it si frequent, the reaction will speed up.
3)Surface Area
-the greater the surface area the faster the rate of reaction because the partickkes are scattered and the tendency of it is to collide-collisions speeds up chemical reaction
4)catalyst
-a substances that changes the rate of a chemical reaction,the catalyst lowers the reaction so that the reaction will speed up the reaction.
5)Inhibitor
-inhibito, a substance that slows down the chemicl reaction. It is a negative catalyst. it increases the activtion energy.
Mole-the SI Unt for the amount of substance which is equal to 6.02 × 10(23) particles
-1 mole Na=6.02×10(23)Na atoms
-1 mole H2O=6.02×10(23)H2Omolecules
-1 mole NaCl=6.02×10(23)ion pair
-1 mole Cl=6.02×10(23) ions
-2 molesH2O=1.204×10(24)H2O molecule
Kinds of Reaction
;Combination reaction- A+B=AB
;Decomposition eaction- AB= A+B
;Single Replacement- A+BC= AC+B
;Double displacement- AB+CD=AC+BD
Alizza Salando
ReplyDeleteFour Types of Chemical Reaction
CHEMICAL REACTION- a process that involves rearrangement of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction.
1. Combination
- involves several reactants combining to form a single product
-A+B->AB
2. Decomposition
-a single reactant breaks down into several products
-AB->A+B
3. Single Displacement
-an active substance replaces another element from its compound
-A+BC->B+AC
4. Double Displacement
-Two substances exchange atoms or groups of atoms
-AB+CD->AD+BC
ALIZZA SALANDO
ReplyDeletePhysical and Chemical Change
Physical Change-the chemical structure doesn’t change
-gas to solid->deposition
-gas to plasma->ionization
-plasma to gas->de ionization
Examples:
1. crushing a can
2. melting an ice cube
3. boiling water
4. mixing sand and water
5. breaking a glass
6. dissolving sugar and water
7. shredding paper
8. chopping wood
9. mixing red and green marbles
Chemical Change-change that results in the formation of new substance
Examples:
1. rusting of iron
2. combustion (burning) of wood
3. metabolism of food in the body
4. mixing an acid and a base, such as hydrochloric acid (HCl) and sodium hydroxide (NaOH)
5. cooking an egg
6. digesting sugar with the amylase in saliva
7. mixing baking soda and vinegar to produce carbon dioxide gas
8. baking a cake
INDICATORS:
• Formation of precipitate- insoluble gelatinous substance
• Change in temperature
• Changes in color
• Formation of bubbles
• Release or absorption of heat
• Evolution of heat and light
• Production of electrical energy
• Production of mechanical energy
ALIZZA SALANDO
ReplyDeleteFactors Affecting the Rate of a Chemical Reaction:
Occur before a reaction:
1. The reactant particles must collide
2. The collisions must be enough energy to overcome
The energy barrier called the activation energy
3. The reactants must form new bonds to produce products
ACTIVATION ENERGY I
-minimum energy needed to start a chemical reaction
-the minimum energy required to bring about a chemical reaction
IF THERE WERE NO SUCH THING AS ACTIVATION ENERGY, LIFE WOULD BE VERY DIFFICULT.
1. Concentration
-the higher the concentration the faster the chemical reaction
-more particles and collision happen
2. Temperature
-the higher the temperature the faster the chemical reaction
-more kinetic energy
3. Surface Area
-the greater the surface area the faster the rate
-more frequent collision happen
4. Catalyst
-any substance that speeds the chemical reaction without consuming itself
-lowers the activation energy
5. Inhibitor
-any substance that slows down the chemical reaction
-increases the activation energy
ALIZZA SALANDO
ReplyDelete4 TYPES OF CHEMICAL REACTION
There are four types of Chemical reaction. First is COMBINATION which one substance plus one substance to produce a single product. Second is DECOMPOSITION a single reactant to produce two products. Third is SINGLE DISPLACEMENT which active substance replaces another element from its compound. Fourth is DOUBLE DISPLACEMENT which two substances exchange atoms. This different types of reaction can also apply in our life or can relate in our relationship. For me I’ll choose Combination, because it is perfect relationship.
ALIZZA SALANDO
ReplyDeleteReflection:
FACTORS AFFECTING THE RATE OF CHEMICAL REACTION
There are different factors affecting the rate of chemical reaction, CONCENTRATION, TEMPERATURE, SURFACE AREA, CATALYST and INHIBITOR. Each of this factor helps in our daily life. And one of it is temperature. Temperature helps to slow the spoilage of the food. Because the higher the temperature the faster the chemical reaction.
Grace Lydel Ortiz
ReplyDeleteI've learned that not all chemical reactions are bad. When we tackled the lesson "Chemical Reaction" my mind was full of new thoughts about this topic. There are also good things about chemical reaction like when we cook foods. It makes our food more delicious . But also I've learned that there are really bad that may occur during chemical reactions like combustion that may burn our skin and many more, we may even get sick. I've also learned about the 4 kinds of Reaction. Combination Reaction with two or more reactants and form a single product. The decomposition reaction which a single reactants decompose and produce two or more simple substances. Single replacement reaction a single free element replaces for one of the element in a compound. And the Double displacement reaction involved the exchange of ion by two compound to form two different products.
Each and everyone of us don’t know what chemistry subject is when we are in our elementary days. Because it is quite difficult and student hate difficult subject. But when you turn 3rd year and met this subject, you can appreciate what this subject all about. With the help of our teacher Mr. Ronaldo Reyes which I can describe as a very intelligent teacher, he helps us to know what are the applications of our topic in our daily lives. And when he starts to introduce to us the chem-connect project which is the objective is to help not only us but the community itself.
ReplyDeleteAnd now our topic is all about reaction. I knew that simply placing water in the fridge is a reaction. First I don’t believe that reaction which is a deep word just happen when you are just putting some water at the fridge. Well that is physical reaction. When you are lighting a candle, which is a combination of physical and chemical reaction. Because burning a match is chemical reaction also known as combustion and the melting which is the phase of matter. But don’t you know that not all reactions are good and can cause harm to your health? When some elements react with each other, like muriatic acid which is a toilet bowl and tile cleaner when combined with household bleach like zonrox (branded bleach) it can produce harmful gas and also known as chloramine which is a warm heat and can burn your skin and also cause some illness. And not only that, there are more reactions happens in our environment whether it’s good or bad, we must learn how to use and apply this anytime and anywhere.
Chemical change is any change that results in the formation of new chemical substances. At the molecular level, chemical change involves making or breaking of bonds between atoms. These changes are chemical:
ReplyDelete• iron rusting (iron oxide forms)
• gasoline burning (water vapor and carbon dioxide form)
• eggs cooking (fluid protein molecules uncoil and crosslink to form a network)
• bread rising (yeast converts carbohydrates into carbon dioxide gas)
• milk souring (sour-tasting lactic acid is produced)
• suntanning (vitamin D and melanin is produced)
Physical change rearranges molecules but doesn't affect their internal structures. Some examples of physical change are:
• whipping egg whites (air is forced into the fluid, but no new substance is produced)
• magnetizing a compass needle (there is realignment of groups ("domains") of iron atoms, but no real change within the iron atoms themselves).
• boiling water (water molecules are forced away from each other when the liquid changes to vapor, but the molecules are still H2O.)
• dissolving sugar in water (sugar molecules are dispersed within the water, but the individual sugar molecules are unchanged.)
• dicing potatoes (cutting usually separates molecules without changing them.)
gas to solid – deposition
gas to plasma- ionization
plasma to gas- deionization
Solid→Liquid Melting
Liquid→Gas Vaporization
Liquid→Solid Freezing
Gas→Liquid Condensation
Solid→Gas Sublimation
Five Indicators of a Chemical Change
ReplyDeleteThe five signs of chemical change are changes in color, temperature, and odor, production of gas, and precipitation. These chemical changes are called chemical reaction.
Change in Temperature
A change in temperature is characteristic of a chemical change. During an experiment, one could dip a thermometer into a beaker or Erlenmeyer Flask to verify a temperature change. If temperature increases, as it does in most reactions, a chemical change is likely to be occurring. This is different from the physical temperature change. During a physical temperature change, one substance, such as water is being heated. However, in this case, one compound is mixed in with another, and these reactants produce a product. When the reactants are mixed, the temperature change caused by the reaction is an indicator of a chemical change.
Change in Color
A change in color is also another characteristic of a chemical reaction taking place. For example, if one were to observe the rusting of metal over time, one would realized that the metal has changed color and turned orange. This change in color is evidence of a chemical reaction. However, one must be careful; sometimes a change in color is simply the mixing of two colors, but no real change in the composition of the substances in question.
Noticeable Odor
When two or more compounds or elements are mixed and a scent or odor is present, a chemical reaction has taken place. For example, when an egg begins to smell, (a rotten egg) a chemical reaction has taken place. This is the result of a chemical decomposition.
Formation of a Precipitate
The formation of a precipitate may be one of the most common signs of a chemical reaction taking place. A precipitate is defined to be a solid that forms inside of a solution or another solid. Precipitates should not be confused with suspensions, which are solutions that are homogeneous fluids with particles floating about in them. For instance, when a soluble carbonate reacts with Barium, a Barium Carbonate precipitate can be observed.
Formation of Bubbles
The formation of bubbles, or rather a gas, is another indicator of a chemical reaction taking place. When bubbles form, a temperature change could also be taking place. Temperature change and formation of bubbles often occur together. For example, in the following image, one can see a gas spewing. This is the formation of a gas.
REFLECTION
With this lesson I learned how to specify between the two changes. How they differ from each other by their properties and composition. It can be seen through our daily work. And by learning this there are some harmful effects when objects or substance undergo these changes. The indicator of chemical change helps us to identify which is the chemical change when substance undergo. By that it makes easier to know because its properties.
activation energy
ReplyDeleteThe least amount of energy needed for a chemical reaction to take place. Some elements and compounds react together naturally just by being close to each other, and their activation energy is zero. Others will react together only after a certain amount of energy is added to them. Striking a match on the side of a matchbox, for example, provides the activation energy (in the form of heat produced by friction) necessary for the chemicals in the match to ignite. Activation energy is usually expressed in terms of joules per mole of reactants
FACTORS THAT AFFECT THE RATE OF CHAMICAL REACTION
1. 1. Increasing the temperature causes the particles (atoms
or molecules) of the reactants to move more quickly so that
they collide with each other more frequently and with more
energy. Thus, the higher the temperature, the greater the rate
of reaction. If you decrease the temperature, the opposite
effect occurs. The particles move more slowly, colliding
less frequently and with less energy. In this case, the rate of
reaction decreases.
2. Concentration refers to how much solute is dissolved in
a solution.
If a greater concentration of reactant atoms and molecules
is present, there is a greater chance that collisions will occur
among them. More collisions mean a higher reaction rate.
Thus, increasing the concentration of the reactants usually
results in a higher reaction rate. At lower concentrations,
there is less chance for collisions between particles. This means that decreasing the concentrations of the reactants
results in a lower reaction rate.
3. Surface area is the measure of how much area of an
object is exposed.
For the same mass, many small particles have a greater total
surface area than one large particle. For example, steel wool
has a larger surface area than a block of steel of the same
mass. This allows oxygen molecules to collide with many
more iron atoms per unit of time. The more surface contact
between reactants, the higher the rate of reaction. The less
surface contact, the lower the reaction rate.
Surface area can also be important if a reaction occurs
between two liquids that do not mix. In this case, the reaction
occurs only at the boundary where the two liquids meet. It is
also important to note that not all reactions depend on surface
area. If both reactants are gases or liquids that mix together,
then there is no surface, and surface area is not a factor.
4. A catalyst is a substance that speeds up the rate of a
chemical reaction without being used up in the reaction itself.
Catalysts reduce the amount of energy required to break and
form bonds during a chemical reaction. When catalysts are
used, a reaction can proceed although less energy is added
during the reaction. For example, enzymes are catalysts
that allow chemical reactions to occur at relatively low
temperatures within the body
5. An inhibitor is a substance that delays, slows or prevents a chemical reaction. Also called the negative catalyst.
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another.
ReplyDelete• Direct Combination or Synthesis Reaction
In a synthesis reaction two or more chemical species combine to form a more complex product.
A + B → AB
The combination of iron and sulfur to form iron (II) sulfide is an example of a synthesis reaction:
8 Fe + S8 → 8 FeS
• Chemical Decomposition or Analysis Reaction
In a decomposition reaction a compound is broken into smaller chemical species.
AB → A + B
The electrolysis of water into oxygen and hydrogen gas is an example of a decomposition reaction:
2 H2O → 2 H2 + O2
• Single Displacement or Substitution Reaction
A substitution or single displacement reaction is characterized by one element being displaced from a compound by another element.
A + BC → AC + B
An example of a substitution reaction occurs when zinc combines with hydrochloric acid. The zinc replaces the hydrogen:
Zn + 2 HCl → ZnCl2 + H2
• Metathesis or Double Displacement Reaction
In a double displacement or metathesis reaction two compounds exchange bonds or ions in order to form different compounds.
AB + CD → AD + CB
An example of a double displacement reaction occurs between sodium chloride and silver nitrate to form sodium nitrate and silver chloride.
NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)
A Mole is:
ReplyDelete• 6.02 x 1023 of anything.
• The formula mass in grams of a substance contains one mole of particles.
• Na = Avogadro's Number = 6.02 x 1023 Spreading a "mole" of marbles over the entire surface of the earth would produce a layer about three miles thick.
When will the World's computers have a mole of digital data stored in them?
Important mole conversion factors:
1 mole = 6.02 x 1023 particles = formula mass in grams
Molar mass - the mass of a single atom of an element (in amu) is numerically equal to the mass of one mole of those atoms (in grams).
From the Periodie Table, the mass of one atom of chromium is 51.9961 amu.
The mass of one mole (6.02 X 1023) of chromium atoms is 51.9961 grams.
Coefficients in a chemical equation are normally used to indicate a ratio of reacting molecules. They also indicate a ratio of reacting moles. The mole concept allows chemists to use chemical equations to determine the "weight" of reactants and products in chemical reactions.
For example: 2Mg(s) + O2 (g) → 2MgO(s)
The balanced equation above shows that the product is 2 molecules of magnesium oxide. That also means 2 moles of magnesium oxide. By calculating the molar mass of MgO, then multiplying by the coefficient 2, the mass of MgO produced can be predicted from the balanced equation.
REFLECTION
ReplyDeleteThese topics helped me to know more about chemical reaction. There are factors that affect chemical reaction that can speed up or slows the reaction depending on factor affecting the substance. Chemical reaction transforms substance to another. There are 4 main chemical reaction one that combine, break to pieces, being displaced and exchanging bond. I also learned about mole which is a unit of measurement which is used in measuring particles. Moles give us a consistent method to convert between atoms/molecules and grams. It's simply a convenient unit to use when performing calculations. you may not find it too convenient when you are first learning how to use it, but once you become familiar with it, a mole will be as normal a unit as, say, a dozen or a byte.
reflection
ReplyDeleteWell I must say that I agree. For all the details they talked about but the thing that facinates me , that chemical bonds can be compared to human relationships .IMAGINE that! Cool!!
Like COMBINATION a person (male or female) are inlove to each other , a couple, so it is considered combination. While DECOMPOSITION is a reaction that is related to brake ups (awww) . SINGLE DISPLACEMENT is a reaction related to brake up but one person finds another leaving the other alone. THE DOUBLE DISPLACEMENT are like the 2 couple that broke up but they found new partner unlike single displacement.
See ? Chemistry is awesome. Its not only about mole concepts,chemical bonding,molecular geometry but it is about the things around us. The air we breathe , the soil and others even a person like you.
JAN AIRISH BUENDIA
ReplyDeletePHYSICAL CHANGE
~ Involves changes in physical properties, such us size, shape, and density, or changes in phase ( solid to gas, liquid to solid) without undergoing a change in the composition of the substances.
EXAMPLES:
1.crushing a can
2.breaking a glass
3.dissolving sugar and water
4.shredding paper
5.chopping wood
CHEMICAL CHANGE
~In a chemical change, matter undergoes changes in its composition and/or structure. New substances are formed that have different properties and composition from the original material.
EXAMPLES:
1.rusting of iron
2.exploding of dynamite
3.digestion of food
4.moldy cheese
5.souring milk
INDICATORS OF CHEMICAL CHANGE:
~Change in color
~Formation of precipitate/a solid compound
~Emission of odor or smell
~Formation of bubbles
~Change in temperature
~Evolution of heat and light
~Production of electrical energy
~Production of mechanical energy
Cherry Ann Siarez
ReplyDeleteChemical Changes
Chemical changes take place on the molecular level. A chemical change produces a new substance. Examples of chemical changes include combustion (burning), cooking an egg, rusting of an iron pan, and mixing hydrochloric acid and sodium hydroxide to make salt and water.
Physical Changes
Physical changes are concerned with energy and states of matter. A physical change does not produce a new substance. Changes in state or phase (melting, freezing, vaporization, condensation, sublimation) are physical changes. Examples of physical changes include crushing a can, melting an ice cube, and breaking a bottle.
There are many changes happens in our surroundings, Just observe and open your eyes to see the different changes happens in our world.
Cherry Ann Siarez
ReplyDeleteINDICATORS OF CHEMICAL AND PHYSICAL REACTIONS
A chemical change makes a substance that wasn't there before. There may be clues that a chemical reaction took place, such as light, heat, color change, gas production, odor, or sound. The starting and ending materials of a physical change are the same, even though they may look different.
there are several indicators of reaction.You can see the changes happens when you observe. the changes may be in appearance or its internal structure. These are called the indicators.
Cherry Ann Siarez
ReplyDeleteExamples of Chemical Changes
burning wood
dissolving salt in water
mixing acid and base
digesting food
Examples of Physical Changes
crumpling a sheet of paper
melting an ice cube
casting silver in a mold
breaking a bottle
Above are several reaction of Chemical reaction.
Cherry Ann Siarez
ReplyDeleteA chemical reaction is a process that leads to the transformation of one set of chemical substances to another.[1] Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes may both occur.
Reaction types
Combination Reaction
In a synthesis reaction, two or more simple substances combine to form a more complex substance. These reactions are in the general form:
A + B \longrightarrow AB
Two or more reactants yielding one product is another way to identify a synthesis reaction. One example of a synthesis reaction is the combination of iron and sulfur to form iron(II) sulfide:
8Fe + S_8 \longrightarrow 8FeS
Another example is simple hydrogen gas combined with simple oxygen gas to produce a more complex substance, such as water.[18]
Decomposition
Main article: Decomposition reaction
A decomposition reaction is the opposite of a synthesis reaction, where a more complex substance breaks down into its more simple parts. These reactions are in the general form:[18][19]
AB \longrightarrow A + B
One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:
2H_2O \longrightarrow 2H_2 + O_2
Single replacement
In a single replacement reaction, a single uncombined element replaces another in a compound; in order words, one element trades places with another element in a compound[18] These reactions come in the general form of:
A + BC \longrightarrow AC + B
One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:
Mg + 2H_2O \longrightarrow Mg(OH)_2 + H_2
Double replacement
In a double replacement reaction, the anions and cations of two compounds switch places and form two entirely different compounds.[18] These reactions are in the general form:[19]
AB + CD \longrightarrow AD + CB
For example, when barium chloride (BaCl2) and magnesium sulfate (MgSO4) react, the SO42- anion switches places with the 2Cl- anion, giving the compounds BaSO4 and MgCl2.
Another example of a double displacement reaction is the reaction of lead(II) nitrate with potassium iodide to form lead(II) iodide and potassium nitrate:
Pb(NO_3)_2 + 2 KI \longrightarrow PbI_2 + 2 KNO_3
There are 45 types of Chemical reaction that leads to changes happens in this world.
MOLES
ReplyDelete--it is the SI unit for the amount of substanse which is equal to 6.02 x 10 to the 23 power.
there are many particles such as:
MOLECULES-it represent covalent mol. or compounds.
ex: water mol.
ammonia
ATOM-it represent an element
examples are:Na/sodium
Cl/chlorine
S/sulfur
another is ION PAIR/FORMULA UNIT-represent an ionic substance...
examples are:sodium chloride
calcium oxide
also we have the IONS-for the charge element
_
example is:Cl
The 6.02 x 10 to the 23 power is called the AVOGADROS NUMBER by amedeo avogadro ,an Italianb scientist.It is represented in symbol N.And the no. of moles is by n.
The significance of this is that we are able to determine the type of a particle w/c is whether a molecule,a n ion, an ion pair, or an atom....