|Type:Non-Metal, Carbon group||Atomic weight:12.011|
|Density @ 293 K:2.267 g/cm3 (graphite), 3.513 g/cm3 (diamond)||Atomic volume:5.31 cm3/mol (graphite), 3.42 cm3/mol (diamond)|
Carbon has been known since ancient times in the form of soot, charcoal, graphite and diamonds. Ancient cultures did not of course realize that these substances were different forms of the same element. 'Carbon' is derived from the Latin carbo, meaning charcoal.
|State (s, l, g):solid|
|Melting point:3823 K (3550 °C)||Boiling point:4300 K (4027 °C)|
|Specific heat capacity: 0.71 J g-1 K-1 (graphite), 0.5091 J g-1 K-1 (diamond)||Heat of atomization:717 kJ mol-1|
|Heat of fusion:117 kJ mol-1 (graphite)||Heat of vaporization :710.9 kJ mol-1|
|1st ionization energy:1086.5 kJ mol-1||2nd ionization energy:2352.6 kJ mol-1|
|3rd ionization energy:4620.5 kJ mol-1||Electron affinity:121.55 kJ mol-1|
|Shells:2,4||Electron configuration: [He] 2s2 2p2|
|Minimum oxidation number: -4||Maximum oxidation number:4|
|Min. common oxidation no.: -4||Max. common oxidation no.:4|
|Electronegativity (Pauling Scale):2.55||Polarizability volume:1.8 Å3|
|Structure:hexagonal layers (graphite), tetrahedral (diamond)||Color:black (graphite), transparent (diamond)|
|Hardness:0.5 mohs (graphite), 10.0 mohs (diamond)|
Pure carbon has very low toxicity. Inhalation of large quantities of carbon black dust (soot/coal dust) can cause irritation and damage to the lungs.
Carbon can exist in several allotropes, including graphite, diamond, amorphous carbon, fullerines and nanotubes. (The structures of eight allotropes are shown at the bottom of this page.)
Carbon (coal) is used as a fuel.
Graphite is used as a lubricant, for pencil tips, high temperature crucibles, dry cells and electrodes.
Diamonds are used in jewelry and - because they are so hard - in industry for cutting, drilling, grinding, and polishing.
Carbon black is used as the black pigment in printing ink.
Carbon can form alloys with iron, of which the most common is carbon steel. The 14C radioactive isotope is used in archaeological dating. Carbon compounds are important in many areas of the chemical industry.
Carbon forms a vast number of compounds with hydrogen, oxygen, nitrogen and other elements. Its ability to form long-chained, complex compounds has resulted in carbon acting as the basis of all life on Earth.
The outstanding physical properties - for example thermal conductivity and strength - of new carbon allotropes, such as nanotubes, show enormous potential for future development.
|Reaction with air:vigorous, ⇒ CO2||Reaction with 6 M HCl:none|
|Reaction with 15 M HNO3:mild, w/ht ⇒ C6(CO2H)6 (mellitic/graphitic acid)||Reaction with 6 M NaOH:none|
|Oxide(s):CO , CO2||Chloride(s):CCl4|
|Hydride(s):CH4 and many CxHy|
|Atomic radius:70 pm||Ionic radius (1+ ion):pm|
|Ionic radius (2+ ion):pm||Ionic radius (3+ ion):pm|
|Ionic radius (2- ion):pm||Ionic radius (1- ion):pm|
|Thermal conductivity:25-470 W m-1 K-1 (graphite) 470 W m-1 K-1 (diamond)||Electrical conductivity:0.07 x 106 S cm-1|
|Abundance earth's crust: 200 parts per million by weight, 344 parts per million by moles|
|Abundance solar system: 3,000 parts per million by weight, 300 parts per million by moles|
|Cost, pure: $2.4 per 100g|
|Cost, bulk:$ per 100g|
Carbon can be obtained by burning organic compounds with insufficient oxygen. The four main allotropes of carbon are graphite, diamond, amorphous carbon and fullerines. Natural diamonds are found in kimberlite from ancient volcanoes. Graphite can also be found in natural deposits. Fullerenes were discovered as byproducts of molecular beam experiments in the 1980's. Amorphous carbon is the main constituent
13 whose half-lives are known, with mass numbers 8 to 20. Of these, two are stable, 12C and 13C. Isotope 14C, with a half-life of 5730 years, is widely used to date carbonaceous materials such as wood, archeological specimens, etc for ages up to about 40,000 years.