In chemistry, a chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions.
Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together in a defined spatial arrangement by chemical bonds.
Chemical compounds can be molecular compounds held together by:
- covalent bonds,
- salts held together by ionic bonds,
- intermetallic compounds held together by metallic bonds,
- or complexes held together by coordinate covalent bonds.
Pure chemical elements are not considered chemical compounds, even if they consist of molecules that contain only multiple atoms of a single element (such as H2, S8, etc.), which are called diatomic molecules or polyatomic molecules.