Question

1. which element is most likely to have the highest ionization energy? barium magnesium sodium neon

Explanation:

Ionization energy increases across a period and decreases down a group on the periodic - table. Neon is a noble gas with a full outer - shell electron configuration, making it very stable and difficult to remove an electron from. Barium, magnesium, and sodium are metals and have relatively lower ionization energies compared to neon as they tend to lose electrons more easily to achieve a stable configuration.

Answer:

Neon