Which has a higher ionization energy: chlorine (Cl) or magnesium (Mg)? Why? Select the best answer. (1 point)

Question

A. Cl: it takes less energy to add an electron to a valence shell that is nearly full.
B. Cl: it takes much more energy to pull an electron away from a valence shell that is nearly full.
C. Mg: it takes more energy to pull two electrons away from magnesium (Mg) than it does to take them from chlorine (Cl).
D. Mg: magnesium has more valence electrons than chlorine.

Answer 1

The correct answer is B. Cl: it takes much more energy to pull an electron away from a valence shell that is nearly full.

Chlorine has a higher ionization energy than magnesium because chlorine has seven valence electrons and is just one electron short of achieving a full octet configuration (which is energetically favorable). Therefore, removing an electron from chlorine requires significantly more energy. In contrast, magnesium has two valence electrons and is more willing to lose those electrons to achieve a stable electron configuration, resulting in a lower ionization energy compared to chlorine.