Chapter 11, Problem 63E

Interpretation Introduction

Interpretation:

The reason for the decrease in atomic size from left to right in a row is to be stated.

Concept Introduction:

On moving from left to right in a periodic table, the effective nuclear charge increases. The effective nuclear charge pulls the valence electrons closer to the nucleus. Thus, the atom becomes smaller.

On moving from top to bottom in the group, the higher principal energy levels become farther from the nucleus. Therefore, the effective nuclear charge cannot pull the valence electrons closer to the nucleus. Thus, the atom size becomes larger.