How many valence electrons do Group 2 elements have?

Elements in Group 2 of the periodic table, known as alkaline-earth metals, have two valence electrons.

These elements—beryllium, magnesium, calcium, strontium, barium, and radium—possess an electronic structure characterized by a pair of s electrons in their outermost orbital, situated outside a stable, noble-gas-like core. Because these two valence electrons are relatively easy to remove, the chemistry of Group 2 elements is typically dominated by the formation of doubly charged $M^{2+}$ ions.1