Carbon is a solid non-metal element. Pure carbon can exist in very different forms. The most common two are diamond and graphite. The table shows some differences between them. Diamond is the hardest natural substance on Earth, but it is also very brittle and will shatter if hit with a hammer.
Graphite is unusual because it is a non-metal that conducts electricity. As a result of the disaster, the Command Module was extensively redesigned to prevent such a tragedy from occurring again. Oxygen is used in welding to generate the intense heat needed to cut and weld steel and other high-melting point metals.
It is used in hospitals to supply oxygen to patients who have difficulty breathing. It is also used in rocket fuels: the Saturn V rockets that launched the Apollo lunar missions used , gallons of kerosene and , gallons of liquid oxygen in its first stage S-IC , and , gallons of liquid hydrogen and 83, gallons of liquid oxygen in its second stage S-II , and 69, gallons of liquid hydrogen and 20, gallons of liquid oxygen in its third S-IVB stage; the Space Shuttle main engines use , gallons of liquid hydrogen and , gallons of liquid oxygen.
The discovery of oxygen is an extremely tangled story, partially because of questions of priority, and partially because of misunderstandings about the nature of combustion and the gas phase. For thousands of years, air was considered to be an "element," and it was not recognized that air was actually a mixture of many different gases.
The nature of combustion was also hotly debated pun intended ; many scientists believed that flammable substances contained a material called phlogiston , which was released when a substance burned.
When nitrogen was discovered in , it was referred to as "phlogisticated air," since an atmosphere of pure nitrogen actually, nitrogen plus carbon dioxide did not support combustion. It was thought that this "air" had absorbed the maximum amount of phlogiston.
Oxygen was discovered by the Swedish chemist Carl Wilhelm Scheele in , but his account of his experiment was not published until The English chemist Joseph Priestley produced oxygen in by heating a sample of merucry II oxide, HgO, and collecting the oxygen gas it produced over water. He called the gas "dephlogisticated air," since it supported combustion more vigorously that "normal" air, and therefore presumably was more capable of "pulling" phlogiston out of other substances.
The French chemist Antoine Lavoisier claimed to have produced oxygen in , independently of Priestley, but Priestley had visited him a few months before and told him of his experiment.
Lavoisier did, however, correctly interpret the significance of Priestley's result: that combustion is the not release of phlogiston from a substance, but the combination of the substance with oxygen in the air, to produce oxides as well as heat and light.
Lavoisier believed that the new element was an essential component of all acids, and proposed that it be called "oxygen," from the Greek words oxy , "acid" and genes "forming.
Another well-known form of oxygen is ozone , O 3. Ozone is a powerful oxidizing agent, and is often used to kill bacteria during the purification of water. At sea level, ozone in the atmosphere is a pollutant, produced by the action of sunlight on nitrogen oxides in car exhaust. In the stratosphere, at an elevation of 10 to 50 km about the surface of the Earth, ozone is produced by the action of sunlight upon O 2 , which splits apart into atomic oxygen, O, and combines with another O 2 molecule to form ozone, O 3.
The ozone absorbs high-energy ultraviolet light, splitting apart into O 2 and O, which can then recombine and absorb another photon of high-energy light. This ozone layer forms a shield which protects living organisms on the Earth's surface from this damaging, high-energy light.
The release of CFCs chlorofluorocarbons into the atmosphere produces chlorine radicals which are damaging to the ozone layer; for this reason, these substances are being phased out. See the Molecules pages on dichlorodifluoromethane for more information. This is unusual for the solid form of a liquid substance, and one reason why if you're sailing in a ship in the North Atlantic, it's a good idea to keep a lookout for icebergs.
These "anomalous" properties of water are in part a result of the large differences in electronegativity between oxygen and hydrogen — the oxygen-hydrogen bond is extremely polar, and water molecules attract each other much more strongly than most other small molecules do, as a results of these hydrogen bonds. See the entry on hydrogen for more on hydrogen bonds. Recycling rate The percentage of a commodity which is recycled.
Substitutability The availability of suitable substitutes for a given commodity. Reserve distribution The percentage of the world reserves located in the country with the largest reserves. Political stability of top producer A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.
Political stability of top reserve holder A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators. Supply risk. Relative supply risk 3. Young's modulus A measure of the stiffness of a substance. Shear modulus A measure of how difficult it is to deform a material.
Bulk modulus A measure of how difficult it is to compress a substance. Vapour pressure A measure of the propensity of a substance to evaporate. Pressure and temperature data — advanced. Listen to Sulfur Podcast Transcript :. You're listening to Chemistry in its element brought to you by Chemistry World , the magazine of the Royal Society of Chemistry. Hello, this week stinky sediments, skunks and the smell of hell. Well they all begin with the letter S, and so does this week's element.
Here's Steve Mylon. The smell of the sediment tells a great deal about the underlying chemistry. Thick black anoxic sediments can be accompanied by a putrid smell which is unique to reduced sulfur. Maybe this is why sulfur has such a bad reputation.
My son wouldn't eat eggs for 6 months when he got a smell of his first rotten one. In the bible it seems that whenever something bad happens or is about to happen burning sulfur is in the picture:.
And in Revelation we read that the sinners will find their place in a fiery lake of burning sulfur. The odd thing is that in both cases we shouldn't expect anything smelly to be produced. When sulfur burns in air, it generally forms sulfur dioxide or sulfur trioxide, the latter of which lacks any smell [amended from the podcast audio file, which states that sulfur dioxide does not smell].
These compounds can further oxidize and rain out as sulfuric or sulfurous acid. This is the mechanism for acid rain which has reeked havoc on the forests of the northeastern United States as sulfur rich coals are burned to generate electricity in midwestern states and carried east by prevailing winds where sulfuric acid is rained out causing all sorts of ecological problems.
Additionally, the combination of burning coal and fog creates smog in many industrial cities causing respiratory problems among the locals. Here too, sulfur dioxide and sulfuric acid are implicated as the culprits. But again, there is no smell associated with this form of sulfur. But reduce sulfur by giving it a couple of electrons, and its smell is unmistakable.
The requirement of sulfur reduction to sulfide has clearly been lost in translation. Hell that smells like hydrogen sulfide or any number of organic-sulfur compound will not be a nice place at all. The organic sulfide compounds known as thiols or mercaptans smell so bad, that they are commonly added to odorless natural gas in very small quantities in order to serve as a 'smell alarm' should there be leak in a natural gas line. Skunks take advantage of the foul smell of butyl seleno-mercaptan as a means of defending themselves against their enemies.
And for me, personally, the worst chemistry of all occurs when reduced sulfur imparts a bad skunky taste in bottles of wine or beer. So, where does the "smell of hell" come from in anoxic sediments. Interestingly, some bacteria have evolved to make use of oxidized sulfur , sulfate, as an electron acceptor during respiration. In a similar manner to the way humans reduce elemental oxygen to water, these bacteria reduce sulfate to hydrogen sulfide- They clearly don't mind the smell.
Smell is not the only interesting chemistry that accompanies reduced sulfur. The deep black associated with anoxic sediments results from the low solubility of most metal sulfides. Sulfate reduction to sulfide generally accompanies the precipitation of pyrite iron sulfide , cinnabar mercury sulfide , galena lead sulfide and many more minerals. These metal sulfides have become an important industrial source for many of these important metals.
Industry is one place you are almost certain to find sulfur or more importantly sulfuric acid which is used in processes ranging from fertilizer production to oil refining. In fact sulfuric acid ranks as the most highly produced chemical in the industrialized world.
Imagine that, the element with such a hellish reputation has become one of the most important. And some even suggest that sulfur could save the planet. The biogenic compound dimethylsulfide DMS is produced from the cleavage of dimethylsufonoprioponate, an osmotic regulatory compound produced by plankton in the ocean. DMS is oxidized to SO2 and finally to sulfuric acid particles which can act as cloud condensation nuclei forming clouds which have a net cooling effect to the planet.
Imagine warmer temperatures followed by greater biological activity resulting in more DMS to the atmosphere. The resulting cloud formation might work to cool a warming planet. It's almost like the plankton are opening an umbrella made up-in part- of sulfur.
From a symbol of damnation to savior Steve Mylon sniffing out the stinky story of Sulfur. Thankfully next week's element is a lot less odiforous. The story of its discovery started when Rayleigh found that the nitrogen extracted from the air had a higher density than that made by decomposing ammonia.
The difference was small but real. Ramsay wrote to Rayleigh suggesting that he should look for a heavier gas in the nitrogen got from air, while Rayleigh should look for a lighter gas in that from ammonia. Ramsay removed all the nitrogen from his sample by repeatedly passing it over heated magnesium. He was left with one percent which would not react and found it was denser than nitrogen. Its atomic spectrum showed new red and green lines, confirming it a new element.
And that new element was Argon nicknamed the lazy element because originally scientists thought that it wouldn't react with anything. Now we know that's not true and John Emsley will be here to unlock Argon secrets on next week's Chemistry in its Element, I hope you can join us.
I'm Chris Smith, thank you for listening and goodbye. Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists. There's more information and other episodes of Chemistry in its element on our website at chemistryworld. It is also present in extra-cellular fluid eg blood to balance the positive mainly sodium ions.
We get most of the chloride we need from salt. Typical daily salt intake is about 6 grams, but we could manage with half this amount. Natural abundance. Chlorine is not found uncombined in nature. Sodium chloride is a very soluble salt that has been leached into the oceans over the lifetime of the Earth.
Chlorine is also found in the minerals carnallite magnesium potassium chloride and sylvite potassium chloride. This process also produces useful sodium hydroxide. Help text not available for this section currently. Elements and Periodic Table History. Hydrochloric acid HCl was known to the alchemists. The gaseous element itself was first produced in by Carl Wilhelm Scheele at Uppsala, Sweden, by heating hydrochloric acid with the mineral pyrolusite which is naturally occuring manganese dioxide, MnO 2.
A dense, greenish-yellow gas was evolved which he recorded as having a choking smell and which dissolved in water to give an acid solution. He noted that it bleached litmus paper, and decolourised leaves and flowers. Humphry Davy investigated it in and eventually concluded not only that it was a simple substance, but that it was truly an element. He announced this in and yet it took another ten years for some chemists finally to accept that chlorine really was an element.
Atomic data. Bond enthalpies. Glossary Common oxidation states The oxidation state of an atom is a measure of the degree of oxidation of an atom. Oxidation states and isotopes. Glossary Data for this section been provided by the British Geological Survey. Relative supply risk An integrated supply risk index from 1 very low risk to 10 very high risk. Recycling rate The percentage of a commodity which is recycled. Substitutability The availability of suitable substitutes for a given commodity.
Reserve distribution The percentage of the world reserves located in the country with the largest reserves. Political stability of top producer A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.
Political stability of top reserve holder A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators. Supply risk. Young's modulus A measure of the stiffness of a substance. Shear modulus A measure of how difficult it is to deform a material.
Bulk modulus A measure of how difficult it is to compress a substance. Vapour pressure A measure of the propensity of a substance to evaporate. Pressure and temperature data — advanced. Listen to Chlorine Podcast Transcript :. You're listening to Chemistry in its element brought to you by Chemistry World , the magazine of the Royal Society of Chemistry.
What's got three isotopes, keeps swimming pools clean, damages the ozone layer and is used in more chemical synthesis reactions than you can shake a benzene ring at. Well the man with the answer is Tim Harrison. Chlorine is what you might describe as a Jekyll and Hyde element; it is the friend of the synthetic chemist and has found a use in a number of 'nice' applications such as the disinfecting of drinking water and keeping our swimming pools clean.
It also has an unpleasant side, being the first chemical warfare agent and taking some of the blame in the depletion of the Earth's ozone layer. Elemental chlorine is a pale, yellowy green gas at room temperature.
This element was first isolated in by the Swiss-German chemist Carl Wilhelm Scheele, by reacting hydrochloric acid with manganese IV oxide. But he failed to realise his achievement, mistakenly believing it also contained oxygen. It was Davy in who finally concluded that Scheele had made elemental chlorine. Chlorine is in group 17 of periodic table, also called the halogens, and is not found as the element in nature - only as a compound.
The most common of these being salt, or sodium chloride, and the potassium compounds sylvite or potassium chloride and carnallite potassium magnesium chloride hexahydrate. It is also estimated that there are around two thousand organic chlorine compounds. Chlorine has two stable isotopes chlorine and chlorinewith Chlorine accounting for roughly 3 out of every 4 naturally occurring chlorine atoms.
Chlorine is also known naturally and is a radioactive isotope with a half life of about 30, years. Chlorine has a major role to play in synthetic organic chemistry, taking part in three of the most common reaction mechanisms. In the first of these, the photochemical substitution reaction, chlorine reacts with an alkane by replacing one of the hydrogen atoms attached to a carbon forming a chloroalkane.
This radical reaction is initiated by the use of sunlight or ultraviolet light to split diatomic chlorine into two radicals. Chlorine can also react with alkenes via the electrophilic addition mechanism. This time two chlorine atoms add to a molecule across the electron-rich carbon-carbon double bond.
This reaction has to be carried out in the dark to avoid complications with competing free radical substitutions. A third common mechanism is electrophilic substitution, which occurs when chlorine reacts with a benzene ring by replacing a hydrogen atom forming chlorobenzene and hydrogen chloride. This reaction is most commonly known as the Friedal-Crafts reaction. Chlorine also has a multitude of industrial uses.
Including making bulk materials like bleached paper products, plastics such as PVC and the solvents tetrachloromethane, chloroform and dichloromethane.
It is also used to make dyes, textiles, medicines, antiseptics, insecticides and paints. It's best known uses however are probably in making bleaches such as 'Domestos' and in treating drinking and swimming pool waters to make them safe to use and of course its role as a chemical warfare agent.
The treatment of water with chlorine began in London after a cholera outbreak in when the physician and pioneering hygienist John Snow identified a well in Soho as the source of the outbreak.
Chlorine is still used in most sewage treatment works today. Snow also used a compound of chlorine - chloroform with the formula CHCl3 - as an anesthetic to aid the childbirth of two of Queen Victoria's children. The use of chlorine gas as a chemical weapon was pioneered by German chemist Fritz Haber, who is better known for his work with ammonia.
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