Related articles Climate Greenhouse Greenhouse gas Edit | Discuss Article Carbon Alternative meaning: Carbon (computing) boron - carbon - nitrogen   C Si       Full table General Name, Symbol, Number Carbon, C, 6 Chemical series Nonmetals Group, Period, Block 14 (IVA), 2 , p Density, Hardness 2267 kg/m3, 0.5 (graphite) 10.0 (diamond) Appearance black (graphite) colourless (diamond) Atomic properties Atomic weight 12.0107 amu Atomic radius (calc.) 70 (67)pm Covalent radius 77 pm van der Waals radius 170 pm Electron configuration [He]22s22p2 e- 's per energy level 2, 4 Oxidation states (Oxide) 4, 2 (mildly acidic) Crystal structure Hexagonal Physical properties State of matter solid (nonmagnetic) Melting point 3773 K (6332 °F) Boiling point 5100 K (8721 °F) Molar volume 5.29 ×10;10-6 m3/mol Heat of vaporization 355.8 kJ/mol (sublimess) Heat of fusion N/A (sublimess) Vapor pressure 0 Pa Speed of sound 18350 m/s Miscellaneous Electronegativity 2.55 (Pauling scale) Specific heat capacity 710 J/(kg*K) Electrical conductivity 0.061 × 106/m ohm Thermal conductivity 129 W/(m*K) 1st ionization potential 1086.5 kJ/mol 2nd ionization potential 2352.6 kJ/mol 3rd ionization potential 4620.5 kJ/mol 4th ionization potential 6222.7 kJ/mol 5th ionization potential 37831 kJ/mol 6th ionization potential 47277.0 kJ/mol Most stable isotopes {| border="1" cellspacing="0" cellpadding="2" width="100%" iso NA half-life DM DE MeV DP 12C 98.9% C is stable with 6 neutrons 13C 1.1% C is stable with 7 neutrons 14C trace 5730 y beta- 0.156 14N

SI units & STP are used except where noted.

• diamonds (hardest known mineral). Binding structure: 4 electrons in 3-dimensional so-called sp3-orbitals
• graphite (one of the softest substances). Binding structure: 3 electrons in 2-dimensional sp2-orbitals and 1 electron in s-orbitals.
• Covalent bound sp1 orbitals are of chemical interest only.

Lamp black consists of small graphitic areas. These areas are randomly distributed, so the whole structure is isotropic.

So-called 'glassy carbon' is isotropic and as strong as glass. Unlike normal graphite, the graphitic layers are not arranged like pages in a book, but are crumpled like crumpled paper.

Carbon fibers are similar to glassy carbon. Under special treatment (stretching of organic fibers and carbonization) it is possible to arrange the carbon planes in direction of the fiber. Perpendicular to the fiber axis there is no orientation of the carbon planes. The result are fibers with a higher specific strength than steel.

Carbon occurs in all organic life and is the basis of organic chemistry. This nonmetal also has the interesting chemical property of being able to bond with itself and a wide variety of other elements, forming nearly 10 million known compounds. When united with oxygen it forms carbon dioxide which is absolutely vital to plant growth. When united with hydrogen, it forms various compounds called hydrocarbons which are essential to industry in the form of fossil fuels. When combined with both oxygen and hydrogen it can form many groups of compounds including fatty acids, which are essential to life, and esters, which give flavor to many fruits. The isotope carbon-14 is commonly used in radioactive dating.

Table of contents

1 Notable characteristics 2 Applications 3 History 4 Allotropes 5 Occurrence 6 Inorganic compounds 7 Carbon chains 8 Carbon cycle 9 Isotopes 10 Precautions 11 Reference 12 External links

Notable characteristics

Carbon was not created in the big bang due to the fact that it needs a triple collision of alpha particles (helium nuclei) to be produced. The universe initially expanded and cooled too fast for that to be possible. It is produced, however, in the interior of stars in the horizontal branch, where stars transform a helium core into carbon by means of the triple-alpha process.

Applications

Other uses:

• The isotope ¹⁴C, discovered February 27th, 1940, is used in radiocarbon dating.
• Some smoke detectors use tiny amounts of a radioactive isotope of carbon as source of ionizing radiation (Most smoke detectors of this type use an isotope of Americium)
• Graphite is combined with clays to form the 'lead' used in pencils.
• Diamond is used for decorative purposes, and also as drill bits and other applications making use of its hardness.
• Carbon is added to iron to make steel.
• Carbon is used for control rods in nuclear reactors.
• Graphite carbon in a powdered, caked form is used as charcoal for cooking, artwork and other uses.
• Charcoal pills are used in medicine in pill or powder form to adsorb toxins or poisons from the digestive system.

History

Allotropes

In its amorphous form, carbon is essentially graphite but not held in a crystalline macrostructure. It is, rather, present as a powder which is the main constituent of substances such as charcoal and lamp black (soot).

At normal pressures carbon takes the form of graphite, in which each atom is bonded to three others in a plane composed of fused hexagonal rings, just like those in aromatic hydrocarbons. The two known forms of graphite, alpha (hexagonal) and beta (rhombohedral), both have identical physical properties, except for their crystal structure. Graphites that naturally occur have been found to contain up to 30% of the beta form, when synthetically-produced graphite only contains the alpha form. The alpha form can be converted to the beta form through mechanical treatment and the beta form reverts back to the alpha form when it is heated above 1000 °C.

Because of the delocalization of the pi-cloud, graphite conducts electricity. The material is soft and the sheets, frequently separated by other atoms, are held together only by van der Waals forces, so easily slip past one another.

At very high pressures carbon has an allotrope called diamond, in which each atom is bonded to four others. Diamond has the same cubic structure as silicon and germanium and, thanks to the strength of the carbon-carbon bondss, is together with the isoelectronic boron nitride (BN) the hardest substance in terms of resistance to scratching. The transition to graphite at room temperature is so slow as to be unnoticeable. Under some conditions, carbon crystallizes as Lonsdaleite, a form similar to diamond but hexagonal.

Fullerenes have a graphite-like structure, but instead of purely hexagonal packing, also contain pentagons (or possibly heptagons) of carbon atoms, which bend the sheet into spheres, ellipses or cylinders. The properties of fullerenes (also called "buckyballs" and "buckytubes") have not yet been fully analyzed. All the names of fullerenes are after Buckminster Fuller, developer of the geodesic dome, which mimics the structure of "buckyballs".

Occurrence

Graphite is found in large quantities in New York and Texas, the United States; Russia; Mexico; Greenland and India.

Natural diamonds occur in the mineral kimberlite found in ancient volcanic "necks," or "pipes". Most diamond deposits are in Africa, notably in South Africa, Namibia, Botswana, the Republic of the Congo and Sierra Leone. There are also deposits in Source | Copyright