Chapter 10, Problem 10.65P

(a)

Interpretation Introduction

Interpretation:

The formal charge on each atom of ${\text{Al}}_2{\text{Cl}}_6$ and ${\text{I}}_2{\text{Cl}}_6$ molecules is to be determined.

Concept introduction:

Difference between the number of valence electrons of each and every atom and the number of electrons the atom is associated with is the formal charge. It can be calculated as the number of total valence electrons present in that compound minus half of the number of electrons that are shared in a bond minus the number of electrons that are not bound in that molecule. It is used to estimate that in which way electric charge is distributed in that molecule.

Formula to calculate the formal charge of the atom is as follows:

  $\text{Formal}\text{charge}=\left(\begin{array}{l}\text{number}\text{of}\\ \text{valence}\\ \text{electrons}\end{array}\right)-\left(\left(\begin{array}{l}\text{number}\text{of}\\ \text{non-bonding}\\ \text{electrons}\end{array}\right)+\left(\frac{1}{2}\right)\left(\begin{array}{l}\text{number}\text{of}\\ \text{bonding}\\ \text{electrons}\end{array}\right)\right)$        (1)

(b)

Interpretation Introduction

Interpretation:

Among ${\text{Al}}_2{\text{Cl}}_6$ and ${\text{I}}_2{\text{Cl}}_6$ molecule the one with the planar shape is to be explained.

Concept introduction:

The following steps are used to determine the molecular shape of the given molecule.

Step 1: Write the Lewis structure of the given formula and place the atoms.

Step 2: Count all electron groups including bonding and non-bonding pairs around the central atom and use it to assign one of the five electron-group arrangement.

Step 3: Write the ideal bond angle related to the electron-group arrangement and the effect of any deviation can be predicted by using VSEPR.

Step 4: Count the bonding and non-bonding electron groups and draw the molecular shape accordingly.