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 bonds. It belongs to group 14 of the periodic table. Three isotopes occur naturally, 12C and 13C being stable, while 14C is a radionuclide, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity. A fossil fuel formed from dead plants by exposure to heat and pressure in Earth’s crust over millions of years, coal provides about 30 percent of global energy needs.
As for other uses: Diamonds (pure carbon), graphite and fullerenes are allotropes with extremely different properties; amorphous carbon is used as an electrode material in lithium ion batteries; activated charcoal is used as an adsorbent;and buckyballs are hollow spheres composed entirely of carbon atoms. There are more than ten million tons of it produced each year, mostly from petroleum refineries as a precursor to catalysts.