Compound

Compound, in chemistry, any substance composed of atoms of more than one element chemically bonded to form a fixed structure with distinctive properties. Compounds may be separated into two groups: organic (containing carbon atoms) and inorganic (all other compounds). Any compound may be described by a chemical formula that indicates the composition of one of its molecules, the molecule being the smallest unit of that compound to have the characteristics of that compound. The chemical formula for water, for example, is H₂O, which indicates that a molecule of water is made up of two atoms of hydrogen and one atom of oxygen.

See also: Chemistry.