Chapter 2, Problem 2E.21E

(a)

Interpretation Introduction

Interpretation:

Lewis structure of ${\text{C}}_2{\text{H}}_4$ and approximate bond angle has to be predicted.

Concept Introduction:

For molecules that have lone pairs around central atom, lone pairs influence shape, because there are no atoms at the positions occupied by these lone pairs. The key rule that governs the molecular shape, in this case, is the extent of lone pair–lone pair repulsions are far greater than lone bond pair or bond pair-bond pair repulsions. The table that summarized the molecular shapes possible for various combinations of bonded and lone pairs are given as follows:

$\begin{array}{cccc}\text{Steric number}& \text{Number of lone pairs}& \text{Molecular geometry}& \text{Bond angles}\\ 2& 0& \text{Linear}& 180°\\ 3& \begin{array}{c}0\\ 1\end{array}& \begin{array}{c}\text{Trigonal planar}\\ \text{Bent}\end{array}& 120°\\ 4& \begin{array}{c}0\\ 1\\ 2\end{array}& \begin{array}{c}\text{Tetrahedral}\\ \text{Trigonal pyramidal}\\ \text{Bent}\end{array}& 109.5°\\ 5& \begin{array}{c}0\\ 1\\ 2\\ 3\end{array}& \begin{array}{c}\text{Trigonal Bi-pyramidal}\\ \text{See-Saw}\\ \text{T-shaped}\\ \text{Linear}\end{array}& 90°\text{,120 }°,180°\\ 6& \begin{array}{c}0\\ 1\\ 2\end{array}& \begin{array}{c}\text{Octahedral}\\ \text{Square pyramidal}\\ \text{Square planar}\end{array}& 90°\text{,}180°\end{array}$

(b)

Interpretation Introduction

Interpretation:

Lewis structure of $\text{ClCN}$ and approximate bond angle has to be predicted.

Concept Introduction:

Refer to part (a).

(c)

Interpretation Introduction

Interpretation:

Lewis structure of ${\text{OPCl}}_3$ and approximate bond angle has to be predicted.

Concept Introduction:

Refer to part (a).

(d)

Interpretation Introduction

Interpretation:

Lewis structure of ${\text{N}}_2{\text{H}}_4$ and approximate bond angle has to be predicted.

Concept Introduction:

Refer to part (a).