Carbon is the chemical element with symbol C and atomic number 6. Being part of the group 14 on the periodic table, it’s nonmetallic and tetravalent, making four electrons available to form covalent chemical bonds. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity.
There are different structures of this chemic element. The most known are diamond, graphite and amorphous carbon. Depending on its form, carbon’s proprieties vary. For example, diamond is highly transparent, while graphite is opaque and black. Diamonds are along the toughest materials known, while graphite is soft enough to form a streak on paper. Diamond has a very low electrical conductivity, while graphite is a very good conductor. Under normal conditions, diamond has the highest thermarl conductivity of all known materials.
All of the carbon’s structures are solids. They are chemically resistant and require high temperature to react even with oxygen. The most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide. The biggest inorganic carbon sources are dolomites, limestones and carbon dioxide, but also important quantities may be found in organic deposits of peat, coal and oil.
Carbon is the 15th most abundant element in the Earth’s crust and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxrygen. It is present in all known life forms. In the human body carbon is the second most abundant element by mass (about 18.5%) after oxygen.