The ionization energy of atoms
A)decreases going down within a group.
B)increases going down within a group.
C)does not change going down within a group.
D)decreases going across a period.

Question

Quizplus · Accepted Answer

The ionization energy of atoms decreases going down within a group because the distance between the nucleus and valence electrons increases, and therefore the attraction between the nucleus and electrons decreases. As a result, less energy is required to remove an electron from the outermost shell.

The Ionization Energy of Atoms