Chapter 1, Problem 1F.1AST

Interpretation Introduction

Interpretation:

$M{g}^{2+},A{l}^{3+}{\text{, O}}^{2-}and{\text{ S}}^{2-}$ has to be arranged in the increasing order of atomic radius.

Concept Introduction:

Ionic radius is the distance between the atomic nucleus and outermost electron of an ion. From the ionic radius, the size of ions can be visualized

When an atom gets converted to an anion, the charge of nucleus remains the same while the number of electrons increases. This increases the repulsion and hence the electron cloud enlarges which results in the increase in ionic radius.

When an atom gets converted to a cation, the charge of nucleus remains the same while the number of electrons decreases. This decreases the repulsion and hence the electron cloud reduces which results in the decrease in ionic radius.

Down the group, ionic radii increases whereas it decreases along the period (from left to right).