A naturally abundant, nonmetallic element that occurs in all organic compounds and can be found in all known forms of life. Diamonds and graphite are pure forms, and carbon is a major constituent of coal, petroleum, and natural gas. Carbon generally forms four covalent bonds with other atoms in larger molecules. Atomic number 6; atomic weight 12.011; sublimation point above 3,500°C; boiling point 4,827°C; specific gravity of amorphous carbon 1.8 to 2.1, of diamond 3.15 to 3.53, of graphite 1.9 to 2.3; valence 2, 3, 4. See Periodic Table.