Chapter 2, Problem 2F.16E

(a)

Interpretation Introduction

Interpretation:

Bond angle in ${\text{NH}}_2^{-}$ is less than that in ${\text{NH}}_2^{+}$ has to be determined.

Concept Introduction:

The bond angle is the angle formed between two bonded atoms in a covalent species. It decides the molecular geometry of a molecule. For example in molecule ${\text{CH}}_4$, the bond angle is,

The table that relates hybridization with % s character is as follows:

$\begin{array}{cc}\text{Hybridization}& \text{\% s character}\\ \text{sp}& 50\%\\ {\text{sp}}^2& 33\%\\ {\text{sp}}^3& 25\%\end{array}$

Bond angle is directly related to % s character in a molecule.

Hybridization is calculated by the hybrid orbitals and to calculate hybrid orbitals we need to know the steric number that is given by,

  $\text{Steric number}=\left[\begin{array}{c}\left(\text{number of atoms bonded to the central atom}\right)+\\ \left(\text{number of lone pairs on the central atom}\right)\end{array}\right]$        (1)

The table that relates the steric number with hybridization is as follows:

$\begin{array}{cc}\text{Steric Number}& \text{Type of Hybridisation}\\ 2& \text{sp}\\ 3& {\text{sp}}^2\\ 4& {\text{sp}}^3\\ 5& {\text{sp}}^3\text{d}\\ 6& {\text{sp}}^3{\text{d}}^2\end{array}$

(b)

Interpretation Introduction

Interpretation:

Whether $\text{N}2{\text{p}}_{\text{x}}$ orbital participates in ${\text{NH}}_2^{-}$ and ${\text{NH}}_2^{+}$ species or not has to be determined.

Concept Introduction:

Refer to part (a).