What oxidation state do alkaline-earth metals usually have in their compounds?

Alkaline-earth metals, which comprise Group 2 of the periodic table, typically exhibit an oxidation state of +2 in their compounds.12

This chemical behavior is driven by the presence of two valence electrons in the outermost s orbital of these atoms. In chemical reactions, these elements tend to lose both of these electrons to achieve a stable electronic configuration similar to that of a noble gas, resulting in the formation of doubly charged $M^{2+}$ ions. While the energy required to remove the second electron is higher than the first, this cost is compensated for by the binding energy gained through the formation of ionic lattices or interactions with solvents.23

Because the energy required to remove a third electron is prohibitively high, these metals do not exceed a +2 oxidation state in any known chemical environment.2