Alkaline earth metal
= Alkaline earth metal
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An <alkaline earth metal> is a group-2 element, including magnesium, calcium, and barium. A common oxidation state is $+2$, associated with loss of two outer-shell electrons.
The resulting salts can nevertheless have very different solubilities and lattice properties. Comparing magnesium and calcium carbonates or hydroxides shows why periodic similarity does not eliminate the role of ion size, hydration, and crystal structure.