How do ionization energies vary across a period from the left to the right of the periodic table?
A) They consistently decrease.
B) They consistently increase.
C) They generally decrease, but there are some exceptions.
D) They generally increase, but there are some exceptions.

Question

Quizplus · Accepted Answer

Ionization energies generally increase from left to right across a period due to increasing nuclear charge and decreasing atomic radius. However, there are some exceptions such as the dip in ionization energy observed between groups 2 and 3 (e.g. Mg to Al). This is due to the filled subshell of the group 3 element (Al) which makes it easier to remove an electron compared to the group 2 element (Mg) that has a partially filled subshell.

How Do Ionization Energies Vary Across a Period from the Left