Any substance in which two or more chemical element s other than carbon are combined, nearly always in definite proportions (see bonding ), as well as some compound s containing carbon but lacking carbon-carbon bonds (e.g., carbonate s, cyanide s).
Inorganic compounds may be classified by the elements or groups they contain (e.g., oxides, sulfate s). The major classes of inorganic polymer s are silicone s, silane s, silicates, and borates. Coordination compounds (or complexes), an important subclass of inorganic compounds, consist of molecules with a central metal atom (usually a transition element ) bonded to one or more nonmetallic ligand s (inorganic, organic, or both) and are often intensely coloured. See also organic compound .