Chapter 10, Problem 10.84P

(a)

Interpretation Introduction

Interpretation:

The position of substitution of the first two fluorine atoms in ${\text{PCl}}_5$ is to be identified.

Concept introduction:

VSEPR theory is based on the repulsions between the electrons pair in the valence shell. According to VSEPR theory, the shape of a molecule depends on the position of the electron pairs to minimize the repulsion, and maximize the stability.

According to VSEPR theory, the table for molecular geometries when the central atom has no lone pair is as follows:

$\begin{array}{cc}\text{Electron}\text{groups}& \text{Geometry}\\ \text{2}& \text{Linear}\\ \text{3}& \text{Trigonal}\text{Planar}\\ \text{4}& \text{Tetrahedral}\\ \text{5}& \text{Trigonal}\text{bipyramidal}\\ \text{6}& \text{Octahedral}\end{array}$

(b)

Interpretation Introduction

Interpretation:

Among the 5 fluorine containing molecules, the one with the zero dipole moment from is to be identified.

Concept introduction:

Dipole moment arises when there is a separation of charges between two ions or atoms involved in the bond. The dipole moment is a vector quantity and its direction towards the most electronegative atom.

The direction of the dipole moment is represented as follows:

The polar and non-polar molecule can be identified on the basis of the net dipole moment. Polar molecules have non zero value of net dipole moment and the nonpolar molecules have zero net dipole moment.