From Wikipedia, the free encyclopedia
Jump to: navigation, search

In chemistry, a divalent (sometimes bivalent[1]) element, ion, functional group or molecule has a valence of two. Valency is the number of chemical bonds formed, which may be covalent, polar covalent or ionic.


Divalent elements include calcium and sulfur. While the bonds formed by calcium are ionic; sulfur can form covalent bonds as in H2S or ionic bonds as in Na2S.
Divalent anions have a charge of -2, for example S2− and SO42−.
Divalent cations have a charge of +2, for example Fe2+ , Ca2+ and Hg22+.
Divalent functional groups include the imino, =NH, and carbonyl, =O.

Water Hardness[edit]

Main article: Water hardness

The divalent cations Ca2+ and Mg2+ contribute to the properties of water which cause it to be hard, such as the formation of limescale.[2]

See also[edit]