Chapter 2, Problem 2D.12E

Interpretation Introduction

Interpretation:

The anions ${\text{N}}^{3-}$, ${\text{O}}^{2-}$, ${\text{Cl}}^{-}$ and ${\text{Br}}^{-}$ has to be arranged in order of increasing polarizability and reason behind the arrangement has to be explained.

Concept Introduction:

In any polar covalent bond, the difference in electronegativities gives rise to partial positive and negative charges respectively on the cation and anions.

The covalent character is determined with respect to the relative extent of distortion of anionic cloud of anion. For instance, highly charged small alkali metal cation such as ${\text{Li}}^{+}$ is capable to cause polarization in large-sized halides such as iodide ion. Thus there is considerable covalent character in $\text{LiI}$.

In general, greater is the charge on the alkali metal cation or smaller is the size of cation more is its polarizing power to distort the electron cloud of anion. Likewise greater is the polarizability of anion more easily its electron cloud is distorted by a cation.