Atomic Number: 6
Atomic Symbol: C
Atomic Weight: 12.0107
Melting Point: 6,422 F (3,550 C) (diamond)
Boiling Point: 6,872 F (3,800 C) (sublimation)
Word origin: From carbo, the Latin word for charcoal.
Discovery: Carbon was discovered in prehistoric times.
Properties of carbon
Carbon is one of the most abundant elements in the universe; it is plentiful in the stars, sun, comets and the atmospheres of most planets. Some meteorites contain microscopic diamonds, a form of carbon. The energy of stars can be attributed at least in part to the carbon-nitrogen cycle.
Without carbon, the basis for life would be impossible. Carbon is unique among the elements in the vast number and variety of compounds it can form. With hydrogen, oxygen, nitrogen and other elements, it forms a very large number of compounds. There are nearly 10 million known carbon compounds, many thousands of which are essential to life and organic processes. [See Periodic Table of the Elements]
Some of the most important carbon compounds are carbon dioxide, carbon monoxide, carbon disulfide, chloroform, carbon tetrachloride, methane, ethylene, acetylene, benzene, acetic acid and their derivitives.
Graphite, diamonds and fullerenes are the three allotropic forms of carbon. Graphite is one of the softest known materials, while diamond is one of the hardest. Fullerenes are molecules composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. A fourth variation, known as "white" carbon, was first produced in 1969 during the sublimation (transition from solid phase to gas phase without passing through a liquid phase) of pyrolytic graphite at low pressures. White carbon is transparent.
Sources of carbon
Carbon is most commonly obtained in coal deposits. Diamonds are found in volcanic rock, called kimberlite, located in South Africa, Arkansas, and elsewhere. The ocean floor off the Cape of Good Hope is another area where diamonds are being discovered.
In combination, carbon is found as carbon dioxide in the atmosphere and dissolved in all natural waters. Carbon is a component of great rock masses made of calcium, magnesium and iron, which are carbonates. Earth's core contains the planet's largest reservoir of carbon.
Coal, petroleum, and natural gas are primarily hydrocarbons.
About one-third of all industrial diamonds used in the United States are now made synthetically.
Uses of carbon
Carbon has seven isotopes. The International Union of Pure and Applied Chemistry adopted the isotope carbon-12 as the basis for atomic weights in 1961. Because the isotope Carbon-14 has a half-life of 5,715 years, it has been widely used to date wood, archaeological specimens and other items.
Carbon fiber is used as a structural material when a material that is both strong and light-weight is needed.
(Source: Los Alamos National Laboratory)