Question

which element is most likely to form an ion with a negative 2 charge?
oxygen
nitrogen
beryllium
magnesium

Explanation:

Oxygen has 6 valence electrons and needs 2 more to achieve a stable octet. It is likely to gain 2 electrons and form an ion with a - 2 charge. Nitrogen usually forms - 3 ions to gain a stable octet. Beryllium and magnesium are metals and tend to lose electrons to form positive ions.

Answer:

Oxygen