# The periodic table/Carbon
## Discovery

Carbon has been known since prehistoric times. The name is derived from the Latin, carbo, meaning "charcoal".

## Quick Facts

| Name: Carbon Symbol: C Mass: 12.0107 Atomic Number: 6 Electron Configuration: [He] 2s$^2$ 2p$^2$ | Classification: non-metal CAS Number: 7440-44-0:1333-86-4 Appearance: Diamond is a colourless transparent crystalline solid. Graphite is a soft black shiny solid. Fullerenes and graphene are black powders. Discovery in: prehistoric times Key Isotopes: $^{12}$C, $^{13}$C, $^{14}$C Allotropes: diamond, graphite, graphene, amorphous, fullerene | Density: 3.513 g/L (diamond), 2.267 g/L (graphite) Crystal Structure: cubic (diamond), hexagonal (graphite) Melting Point: 3825 °C Boiling Point: sublimes |

## Uses

Carbon can form strongly bonded chains terminated by hydrogen atoms. These are called hydrocarbons, and are extracted naturally as fossil fuels (coal, oil and natural gas). They are mostly used when combusted with oxygen, as a source of energy for transport, electrical energy generation and industry. A small fraction are used as feedstock for the petrochemical industries to produce polymers, fibres, paints solvents, plastics etc. Impure carbon in the form of charcoal (from wood) and coke (from coal) is used in metal smelting, especially for the iron and steel industry. Industrial diamonds are used for cutting rocks and drilling. More recently, the discovery of carbon nanotubes, other fullerenes and graphene are revolutionising developments in the electronics industry and in nanotechnology generally.
150 years ago the natural concentration of carbon dioxide in the earth’s atmosphere was 280 ppm. In 2013, as a result of burning fossil fuels, it was 390 ppm. Atmospheric carbon dioxide allows visible light in but prevents some infra-red escaping (this is the natural greenhouse effect), keeping the Earth warm enough to sustain life. However, an enhanced greenhouse effect due to human-induced rise in atmospheric carbon dioxide is being felt by living things as our climate changes.
The molecules of life are carbon-based. Living things get almost all their carbon from carbon dioxide, either from the atmosphere or dissolved in water, through photosynthesis in green plants and photosynthetic plankton. The sun’s energy splits water into oxygen (released to the atmosphere, into fresh water and the seas) and hydrogen (which joins with carbon dioxide to produce carbohydrates).
With the addition of other elements, especially nitrogen and phosphorus, some of the carbohydrates are used to form the other molecules of life, including bases and sugars for RNA and DNA, and amino acids for proteins. Life forms which do not photosynthesise have to rely on consuming other living things for their source of carbon-based molecules.
Carbon is found in the sun and other stars formed from the debris of a previous supernova, and it is built up by nuclear fusion in bigger stars. It is present in the atmospheres of many planets usually as carbon dioxide. 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. In combination, carbon is found in all living things and as fossilised remains in the form of hydrocarbon gases, crude oil, oil shales and coal etc., and also as carbonates (eg. chalk limestone and dolomite).

## Atomic Data

| Atomic radius: 1.700 Å Covalent radius: 0.75 Å Electronegativity: 2.550 Electron affinity: 121.733 kJ mol$^{-1}$ | Ionisation energies First: 1086.453 kJ mol$^{-1}$ Second: 2352.629 kJ mol$^{-1}$ Third: 4620.467 kJ mol$^{-1}$ Fourth: 6222.711 kJ mol$^{-1}$ Fifth: 37830.615 kJ mol$^{-1}$ Sixth: 47277.133 kJ mol$^{-1}$ |

## Supply Risk
### Coal

Scarcity factor: 4.5 (medium risk)
| Crustal abundance: 200 ppm Reserve base distribution: 27.5% Production concentration: 46.1% | Top 3 countries for mining: USA Russia China | Top 3 countries for production: China USA India |

### Diamond

Scarcity factor: 4.0 (medium risk)
| Crustal abundance: 200 ppm Reserve base distribution: 33.5% Production concentration: 28.6% | Top 3 countries for mining: DRC Australia Botswana | Top 3 countries for production: Russia DRC Botswana |

### Graphite

Scarcity factor: 7.0 (high risk)
| Crustal abundance: 200 ppm Reserve base distribution: 63.6% Production concentration: 81.8% | Top 3 countries for mining: China Czech Republic India | Top 3 countries for production: China Bosnia-Herzegovina Brazil |

## Oxidation States and Isotopes

Common oxidation states: 4, 3, 2, 1, 0, -1, - 2, -3, -4
Isotopes
| Isotope | Atomic mass | Abundance (%) | Half life | Mode of decay |
| $^{12}$C | 12 | 98.93 | | |
| $^{13}$C | 13.003 | 1.07 | | |
| $^{14}$C | 14.003 | | 5717 years | β- |

## Pressure and Temperature Data

Molar heat capacity: 6.155 J mol$^{-1}$ K$^{-1}$ (diamond), 8.157 J mol$^{-1}$ K$^{-1}$ (graphite),

## See Also

* Diamond on Wikipedia
* Allotropes of Carbon on Wikipedia
* Isotropes of Carbon on Wikipedia