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Oxidation & Electrons | Appearance & Characteristics Reactions | Compounds | Radius | Conductivity Abundance & Isotopes 
Models of carbon nanotube structure. |
General:
| Name: Carbon | Symbol: C |
| 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) |
| Discovered: Carbon has been known since ancient times. The name is derived from the Latin carbo, meaning charcoal. | |
States
| State (s, l, g): solid | |
| Melting point: 3823 K (3550 oC) | Boiling point: 4300 K (4027 oC) |
| Note: At normal pressures, carbon does not melt when heated, it sublimes - i.e. when heated, carbon undergoes a phase change directly from solid to gas, much like dry ice (solid carbon dioxide) does. The melting point quoted above is under a pressure of 10 atmospheres. | |
Energies
| 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 (sublimation): 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 |
Oxidation & Electrons
| 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 |
Appearance & Characteristics
| Structure: hexagonal layers (graphite), tetrahedral (diamond) | Color: black (graphite), transparent (diamond) |
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Harmful effects: 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.
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Hardness: 0.5 mohs (graphite), 10.0 mohs (diamond) |
Right: Diamonds (crystalline carbon). We thought about taking a picture of combusting diamonds - they combust at about 800 oC - but we couldn't afford it! 
Carbon based lifeforms, such as those above, dominate our planet. 
Model of DNA. The famous double-helix molecule is made possible by carbon's ability to form long molecular chains. 
Nasa: Carbon nanotubes have outstanding tensile strength - two orders of magnitude higher than graphite fibers, kevlar or steel. |
Characteristics:
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.) Interestingly, graphite is one of the softest substances and diamond was thought, until recently, to be the hardest naturally occurring substance. Now an extremely rare form of carbon, Lonsdaleite, has been calculated, in pure form, to be 58% stronger than diamond. Lonsdaleite is a further allotrope of carbon. It is made when meteorites containing graphite hit another body, such as Earth. The high temperatures and pressures of the impact transform the graphite into Lonsdaleite, a diamond-like substance that retains graphite's hexagonal structure. Carbon has the highest melting/sublimation point of all the elements and, in the form of diamond, has the highest thermal conductivity of any element. This is the origin of the slang term "ice" - diamond, at room temperature, carries heat away from your warmer skin faster than any other material and so feels cold to touch. Uses: 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 forming 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. |
Reactions
| 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 |
Compounds
| Oxide(s): CO , CO2 | Chloride(s): CCl4 |
| Hydride(s): CH4 and many CxHy |
Radius
| 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 |
Conductivity
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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 & Isotopes
| Abundance earth's crust: 1,800 ppm by weight (0.18 %), 3,100 ppm by moles (0.31 %) | |
| Abundance solar system: 3,000 ppm by weight, 300 ppm by moles | |
| Cost, pure: 2.4 $/100g | |
| Cost, bulk: $/100g | |
| Source: Carbon can be made 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 of charcoal, soot (carbon black), and activated carbon. | |
| Isotopes: 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. | |
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A wonderful image released by Michael Ströck under the GNU Free Documentation License: The structures of eight allotropes of carbon:
a) Diamond b) Graphite c) Lonsdaleite d) C60 (Buckminsterfullerene) e) C540 Fullerene f) C70 Fullerene g) Amorphous carbon h) Single-walled carbon nanotube |
