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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.
- 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.
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