Chapter 10, Problem 10.65QP

Interpretation Introduction

Interpretation: The bond moments and the resultant dipole moments of the given molecules have to be sketched out.

Concept Introduction:

Dipole moment:

The term dipole moment refers to the quantitative measure of polarity of a bond. It is represented as $\text{μ}$. It can be defined as the product of the charge $\text{Q}$ and the distance r between the charges. So, its mathematical representation is $\text{μ}\text{=}\text{Q}\times \text{r}$. Dipole moment will be created by the charge separation in a polar molecule.

For example:

The diatomic molecule $\text{HCl}$ possesses dipole moment due to the charge separation in it as shown here:

The crossed arrow represents the direction of the shift of electrons toward the highly electronegative chlorine atom from the least electronegative hydrogen atom.

Bond moment:

In polar molecules, there will be a bond between a high electronegative atom and a least electronegative atom. The high electronegative atom pulls the shared pair of electrons towards itself and acquires a partial negative charge on it and creates a partial positive charge on the least electronegative atom. This is known as charge separation and the overall phenomenon is known as bond moment. It is a vector quantity which means it has both magnitude and direction.

Resultant dipole moment:

If all possible bond moments of a polar molecule are with different magnitudes, then a net dipole moment will be resulted which is known as the resultant dipole moment. If the bond moments are with same magnitudes, then there won’t be a resultant dipole moment since all the bond moments cancel with each other. So, the resultant dipole moment depends on the magnitude of bond moments. It is independent of the directions of bond moments.