The atomic radius of main- group elements generally increases down a group because .
A) the principal quantum number of the valence orbitals increases
B) effective nuclear charge decreases down a group
C) effective nuclear charge increases down a group
D) effective nuclear charge zigzags down a group
E) both effective nuclear charge increases down a group and the principal quantum number of the valence orbitals increases

Question

Quizplus · Accepted Answer

The atomic radius of main-group elements generally increases down a group because the principal quantum number of the valence orbitals increases. As the principal quantum number increases, electrons occupy orbitals that are farther from the nucleus, thus increasing the distance between the nucleus and the outermost electrons and resulting in an increase in atomic radius.

The Atomic Radius of Main- Group Elements Generally Increases Down