Carbon (from Latin: carbo "coal") is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical belongs to group 14 of the periodic table. Carbon makes up only about percent of Earth's crust. Three isotopes occur naturally, 12 C and 13 C being stable, while 14 C is a radionuclide ...