Chapter 2, Problem 23P

Interpretation Introduction

Interpretation:

Each of the following observations is to be explained.

1. ${\text{IF}}_5$ is a polar molecule.

2. The first ionization energy of K is lower than that of Li.

3. ${\text{BI}}_3$ is trigonal planar while ${\text{PI}}_3$ is trigonal pyramidal in shape.

Concept Introduction:

The VSEPR theory provides the simple model for predicting the shapes of molecular species based on minimizing the electrostatic repulsion of a molecule's valence electrons around a central atom.

Electron-electron repulsions decrease in the order:

Lone pair-lone pair > lone pair-bond pair > bond pair-bond pair

A chemical bond where two atoms share a pair of electrons with each other equally is called non polar bond.

A chemical compound where a pair of electrons is unequally shared between two atoms are called polar bond.

Dipole moment ($\text{μ}$) is a measurement of the separation of two opposite electrical charges.

The magnitude is equal to the charge (q) multiplied by the distance between the charges (r) and the direction is from negative charge to positive charge.

$\text{μ = q ×}\text{r}$

First ionization energy is the amount of energy required to remove a loosely bound outermost electron from the isolated gaseous atom.