Divalent
In chemistry, a divalent (sometimes bivalent) 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:
The divalent cations Ca2+ and Mg2+ contribute to the properties of water that cause it to be hard, such as the formation of limescale.
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