Divalent

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.

Examples:

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

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

• Valency (chemistry)
• Valence electron

References