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one of the most important chemical elements, despite making up less than 0.03 per cent of the Earth's crust
Carbon has been known since prehistoric times. The name carbon comes from carbo, or charcoal.
atomic number 6
Calcium does not melt, but it sublimes at about 3,500° C.
At room temperature, pure carbon does not react chemically, but its compounds unite easily with other elements and compounds. Pure carbon will not dissolve in any common solvent.
Pure carbon exists in nature in the form of diamonds, and in graphite, such as that used in some lead pencils. Both forms are pure carbon with different crystal structures. Another form of pure carbon, called amorphous carbon, consists of graphitelike particles too tiny to see without a microscope.
Most carbon, however, occurs in combination with other elements. There are about one million known carbon compounds, which combine in various ways to produce an almost unlimited number of carbon-containing substances. For example, the carbon dioxide in the air is a compound of carbon and oxygen. Other compounds containing carbon include minerals such as limestone (calcium carbonate) and fuels such as coal and petroleum. Carbon compounds make up the living tissues of all animals and plants.
Diamonds are highly prized in and of themselves as precious gems. In diamond, the carbon atoms are arranged in a close framework that makes diamond one of the hardest substances known to man. Diamonds are used to cut other hard materials. In contrast, graphite is so soft that it can be used to lubricate moving machine parts. Its carbon atoms are arranged in flat sheets or layers that can easily slide back and forth over each other.
If oil, natural gas, or other petroleum fuels are burned in limited supplies of air, a powdery-black soot of amorphous carbon, called carbon black (also called lampblack) is formed. Carbon black is used in printing inks, paint, and rubber products.
Animal charcoal, also called boneblack, results from heating bones without exposing them to air. Wood charcoal results from heating wood without enough air to burn it completely. Both kinds of charcoal are used to remove the brown color from sugar and to filter impurities and odors from the air. Charcoal is also used as a cooking fuel.
Coke, an important fuel used in making steel, results from heating soft coal without oxygen, as in making charcoal. Ivory black, made by heating ivory, is sometimes used as a pigment in paint.
Carbon in its almost endless variety of compounds is an indispensable source of such varied everyday products as nylon and gasoline, perfume and plastics, shoe polish and TNT.
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This page was last updated on 10/28/2017.