(1) The combination of a metal ion with a chemical compound, forming a ring.
(2) The binding of a bidentate or multidentate ligand.
Chelation is used in separating and extracting metals, such as in countering and treating heavy metal poisoning. A chelant or chelating agent binds to form a complex with certain metal ions to inactivate the ions so that they cannot normally react with other elements or ions.
Word origin: from Greek chele, meaning claw.