In nature carbon exists in two forms, diamond and graphite, both of which are pure forms. In the diamond form of carbon, the crystal structure is arranged in a close, solid pattern making diamond one of the hardest substances known. Its structure is arranged in flat layers that can move easily. Carbon is commonly used in industrial production of a variety of products. It is found in most plastics and also exists in hydrocarbons, the main element of fuels such as coal, petroleum, and natural gas.
Carbon is able to bond with up to four other elements.
Carbon can form rings, long chains, or a combination of both. It can also form together into tubes and balls. At high temperatures, carbon reacts with sulfur, oxygen, certain metals, and elements of the halogen group.