Which statement correctly compares an atom of an alkali metal with an atom of the alkaline earth metal next to it on the periodic table?

Alkali metals are in Group 1 and typically lose one electron to form +1 ions. The alkaline earth metal beside them in the same period is in Group 2 and typically loses two electrons to form a +2 ion. Their atoms have the same number of electron shells because they are in the same period, so the shell-count statements are incorrect. The correct choice is A: the alkali metal forms a +1 ion, while the alkaline earth metal forms a +2 ion.

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