| Carbon - C
CAS: graphite, 7440-44-0; diamond, 7782-40-3 Description: In pure form as diamonds or graphite Classification: Non-metal Date of Discovery: Known to the ancients Discoverer: Unknown Name Origin: Latin carbo "charcoal" |
|
|
Atomic Number: 6
Number of Neutrons: 6 Atomic Mass: 12.011(1) amu Melting Point:  3500.0 °C;
graphite sublimes at 3825 °C Boiling Point: 4827.0 °C Triple Point: (graphite-liquid-gas) 4492 °C/10.3 MPa (graphite-dia.-liquid) 3830-3930 °C/12-13 GPa Density (25 °C): amorphous, 1.8-2.1 g/cm3 graphite, 1.9-2.3 g/cm3 diamond, 3.15-3.53 g/cm3 Atomic volume: 4.58 cm3/mol Electrical resistivity: 0.00061 10-6/cm 
Thermal conductivity: 1.29 W/cmK Enthalpy of atomization: Enthalpy of vaporization: 355.80 kJ/mol Enthalpy of fusion: 104.60 kJ/mol Specific heat capacity: 0.71 J/gK |
Energy levels: 2-4
Electron configuration: [He]2s22p2 Crystal Structure: Hexagonal (  -graphite)
Atomic radius: 0.91 Å Covalent radius: 0.77 Å Oxidation States: -4, +2, +3, +4 Electronegativity, Pauling: 2.55 Electron affinity: 1.2629 eV First ionization energy: 11.260 eV 2nd ionization energy: 24.383 eV 3rd ionization energy: 47.887 eV Polarizability: 1.76 10-24cm3 |
| Isotope | Natural Abundance | Atomic Mass | Half-life | Decay Mode | Spin |
| 8C | 8.03768 | 2.0 x 10-21 s | p | ||
| 9C | 9.031040 | 127 ms |  +, p, 2 |
(3/2-) | |
| 10C | 10.016853 | 19.3 s | + |
0+ | |
| 11C | 11.011433 | 20.3 m | +, EC |
3/2- | |
| 12C | 98.89(1) | 12.000000 | Stable | 0+ | |
| 13C | 1.11(1) | 13.00335484 | Stable | 1/2- | |
| 14C | 14.00324199 | 5175 y | - |
0+ | |
| 15C | 15.010599 | 2.45 s | - |
1/2+ | |
| 16C | 16.014701 | 0.75 s | - |
||
| 17C | 17.02258 | 0.19 s | - |
||
| 18C | 18.02676 | 0.09 s | -, n |
||
| 19C | 19.0353 | 0.05 s | n | ||
| 20C | 20.0403 | 0.01 s | |||
|
Carbon, an element of prehistoric discovery, is very widely distributed in nature. It is found in abundance in the sun, stars, comets, and atmospheres of most planets. Carbon in the form of microscopic diamonds is found in some meteorites. Natural diamonds are found in kimberlite of ancient volcanic "pipes," such as found in South Africa, Arkansas, and elsewhere. Diamonds are now also being recovered from the ocean floor off the Cape of
Good Hope. About 30% of all industrial diamonds used in the U.S. are now made synthetically. The energy of the sun and stars can be attributed at least in part to the well-known carbon-nitrogen cycle. Carbon is found free in nature in three allotropic forms: amorphous, graphite, and diamond. A fourth form, known as "white" carbon, is
now thought to exist. Graphite is one of the softest known materials while diamond is one of the hardest. Graphite exists in two forms: alpha and beta. These have identical physical properties, except for their crystal structure. Naturally occurring graphites are reported to contain as much as 30% of the rhombohedral (beta) form', whereas
synthetic materials contain only the alpha form. The hexagonal alpha type can be converted to the beta by mechanical treatment, and the beta form reverts to the alpha on heating it above 1000 deg C. In 1969 a new allotropic form of carbon was produced during
the sublimation of pyrolytic graphite at low pressures. Under free-vaporization conditions above ~2550 K, "white" carbon forms as small transparent crystals on the edges of the basal planes of graphite. The interplanar spacings of "white" carbon are identical to those of carbon form noted in the graphitic gneiss from the Ries (meteoritic) Crater of Germany. "White" carbon is a transparent birefringent material. Little information is presently available about this allotrope. Of recent interest is the discovery of all-carbon molecules, known as "buckyballs" or fullerenes, which have a number of unusual properties. These interesting molecules, consisting of 60 (CAS 99685-96-8) or 70 (115383-22-7) carbon atoms linked together, seem capable of withstanding great pressure and trapping foreign atoms inside their network of carbon. They are said to be capable of magnetism and superconductivity and have potential as a nonlinear optical material. Buckyball films are reported to remain superconductive at temperatures as high as 45 K. In combination, carbon is found as carbon dioxide in the atmosphere of the earth and dissolved in all natural waters. It is a component of great rock masses in the form of carbonates of calcium (limestone), magnesium, and iron. Coal petroleum, and natural gas are chiefly hydrocarbons. 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, carbon atom often being linked to carbon atom. There are close to ten million known carbon compounds, many thousands of which are vital to organic and life processes. Without carbon, the basis for life would be imossible. While it has been thought that silicon might take the place of carbon in forming a host of similar compounds, it is now not possible to form stable compounds with very long chains of silicon atoms. The atmosphere of Mars contains 96.2% CO2. Some of the most important compounds of carbon are carbon dioxide (CO2), carbon monoxide (CO), carbon disulfide (CS2), chloroform (CHCl3), carbon tetrachloride (CCl4), methane (CH4), ethylene (C2H4), acetylene (C2H2), benzene (C6H6), ethyl alcohol (C2H5OH), acetic acid (CH3COOH), and their
derivatives. Carbon has thirteen isotopes. Natural carbon consists of 98.89% 12C and 1.11% 13C. In 1961 the International Union of Pure and Applied Chemistry adopted the isotope carbon-12 as the
basis for atomic weights. Carbon-14, an isotope with a half-life of 5715 years, has been widely used to date such materials as wood, archeological specimens, etc.
LINKS: ACS Organic Chemistry Division American Coal Ash Association Home Page Carbon-Carbon Bonds The Carbon Cycle Carbon Monoxide Fact Sheet Carbon monoxide - How to protect your family Chemistry of Carbon Coal Association of Canada The Graphite Page The Mineral Diamond Hydrocarbon Online IUPAC Nomenclature of Organic Chemistry The Nobel Prize in Chemistry 1996 OCR Carbon Dating Organic Chemistry Resources Worldwide Radio-Carbon Dating University of Sussex Fullerene Group Homepage Back Return
Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998. |
|||||