a compound formed by combination of a metal ion in solution with a compound containing heteroatoms (such as oxygen or nitrogen), in which at least two heteroatoms are bound to the metal. The bonds may be covalent or non-covalent. Chelates in some cases have very low dissociation constants, and organic compounds (
chelating agents) which form such chelates are therefore used to reduce the concentration of free metal ions in solution. [
PJC]