Carbon - C General Information Discovery Carbon is an element of prehistoric discovery and is widely distributed in nature. Appearance Can exist as black graphite, the colourless gem diamond, or as fullerenes (the most common of which is C60 and was discovered in 1985). Some scientists regard carbon nanotubes and carbynes as additional allotropic forms. Source Carbon is found in abundance in the sun, stars, comets and atmospheres of most planets. Graphite is found naturally in many locations. Diamond is found in the form of microscopic crystals in some meteorites. Natural diamonds are found in the mineral kimberlite, sources of which are 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 United States are made synthetically. Carbon is found in combination in hydrocarbons (methane gas, oil and coal), and carbonates (limestone and dolomite). Uses Carbon is unique among the elements in the vast number and variey of compounds it can form. With hydrogen, oxygen, nitrogen and other elements it forms very large numbers of compounds, carbon atom often being linked to carbon atom. This ability to form chains is unique to carbon, and is thought to be an important reason for the dependance of life on this element. It is also an indispensable source of such varied everyday products as Nylon and petrol, perfume and plastics, shoe polish, DDT and TNT. Biological Role Carbon is the basis of all life as part of the DNA molecule. There are several million known carbon compounds, many thousands of which are vital to organic and life processes. General Information Carbon is found free in nature in four allotropic forms; amorphous, graphite, diamond and fullerines. Fullerines were first investigated in 1985 with the discovery of Buckminsterfullerene, C60. Graphite is used in lubricants and diamond is one of the hardest known materials. This difference is purely because of the arrangement of atoms in each of the two forms. In graphite, hexagonal rings are joined together to form sheets, and the sheets lie one on top of the other. In diamond, the atoms are arranged tetrahedrally in a vast continuous array. In 1961 the International Union of Pure and Applied Chemistry adopted the isotope carbon-12 as the basis for relative atomic masses. Carbon-14, an isotope with a half-life of 5730 years, has been widely used to date materials such as wood, archeological specimens, etc.

	Physical Information
	Atomic Number		6
	Relative Atomic Mass (12C=12.000)		12.011
	Melting Point/K		3820 (diamond)
	Boiling Point/K		5100 (sublimes)
	Density/kg m-3		3513 (diam.) 2260 (graph.)
	Ground State Electron Configuration		[He]2s22p2
	Electron Affinity(M-M-)/kJ mol-1		-121

	Key Isotopes
	nuclide	12C	13C	14C
	atomic mass	12.000	13.003	14.003
	natural abundance	98.90%	1.10%	trace
	half-life	stable	stable	5730 yrs

Other Information
Enthalpy of Fusion/kJ mol-1		105.0
Enthalpy of Vaporisation/kJ mol-1		710.9
Oxidation States
This concept is rarely used in discussing carbon in its compounds because of subtleties of bonding. However, in single compounds it can be regarded as having oxidation states of C-4, C+2, C+4.
Covalent Bonds /kJ mol-1
C - H	411
C - C	348
C = C	614
C º C	839
C = N	615
C º N	891
C = O	745
C º O	1074

	Ionisation Energies/kJ mol-1
	M - M+	1086.2
	M+ - M2+	2352
	M2+ - M3+	4620
	M3+ - M4+	6222
	M4+ - M5+	37827
	M5+ - M6+	47270