Chelating agents are capable of forming coordinate bonds with metals through two or more atoms of the organic compound. The compound formed by a chelating agent and a metal is called a chelate. A chelating agent that has two coordinating atoms is called bidentate; one that has three, tridentate or ethylenediaminetetraacetate is a common hexadentate-chelating agent. Chlorophyll is a chelate that consists of a magnesium ion joined with a complex chelating agent; heme, part of the hemoglobin in blood, is an iron chelate. Chelating agents are important in textile dyeing, water softening, and enzyme deactivation and as bacteriocides.