Carbon

:Alternative meaning: Carbon (API)

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:For the portable music player, see Rio Carbon

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Carbon is a chemical element in the periodic table that has the symbol C and atomic number 6. An abundant nonmetallic, tetravalent element, carbon has several allotropic forms:

Related Topics:
Chemical element - Periodic table - Atomic number - Nonmetal - Allotropic forms

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• diamond (hardest known mineral). Structure: each atom is bonded tetrahedrally to four others, making a 3-dimensional network of puckered six-membered rings of atoms.
• graphite (one of the softest substances). Structure: each atom is bonded trigonally to three other atoms, making a 2-dimensional network of flat six-membered rings; the flat sheets are loosely bonded.
• fullerenes. Structure: comparatively large molecules formed completely of carbon bonded trigonally, forming spheroids (of which the best-known and simplest is the buckminsterfullerene or buckyball).
• ceraphite (an extremely soft surface). The structure is not certain.
• lonsdaleite (a corruption of diamond). Structure: similar to diamond, but forming a hexagonal crystal lattice.
• amorphous carbon (a glassy substance). Structure: an assortment of carbon molecules in a non-crystalline, irregular, glassy state.
• carbon nanofoam (an extremely light magnetic web). Structure: a low-density web of graphite-like clusters, in which the atoms are bonded trigonally in six- and seven-membered rings.
• carbon nanotubes (tiny tubes). Structure: each atom is bonded trigonally in a curved sheet that forms a hollow cylinder.
• aggregated diamond nanorods, the most recently discovered allotrope.

Lamp black consists of small graphitic areas. These areas are randomly distributed, so the whole structure is isotropic.

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'Glassy carbon' is isotropic and contains a high proportion of closed porosity. Unlike normal graphite, the graphitic layers are not stacked like pages in a book, but have a more random arrangement.

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Carbon fibers are similar to glassy carbon. Under special treatment (stretching of organic fibers and carbonization) it is possible to arrange the carbon planes in direction of the fiber. Perpendicular to the fiber axis there is no orientation of the carbon planes. The result are fibers with a higher specific strength than steel.

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Carbon occurs in all organic life and is the basis of organic chemistry. This nonmetal also has the interesting chemical property of being able to bond with itself and a wide variety of other elements, forming nearly 10 million known compounds. When united with oxygen it forms carbon dioxide which is absolutely vital to plant growth. When united with hydrogen, it forms various compounds called hydrocarbons which are essential to industry in the form of fossil fuels. When combined with both oxygen and hydrogen it can form many groups of compounds including fatty acids, which are essential to life, and esters, which give flavor to many fruits. The isotope carbon-14 is commonly used in radioactive dating.

Related Topics:
Life - Organic chemistry - Oxygen - Carbon dioxide - Plant - Hydrogen - Hydrocarbon - Fossil fuel - Fatty acid - Isotope - Carbon-14 - Radioactive dating

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Carbon: Notable characteristics ►