Chapter 2, Problem 2.42P

Interpretation Introduction

Interpretation:

It is to be explained how the molecules with the general formula ${\text{CX}}_{\text{2}}{\text{Y}}_{\text{2}}$ (where $\text{X}$ and $\text{Y}$ are either a hydrogen or a halogen atom) are always polar, support the tetrahedral geometry and rule out the square planar geometry.

Concept introduction:

The dipole moment of a molecule is a measure of the magnitude of its dipole. A dipole moment is a vector, which has both magnitude and direction. Bond polarity originates from bonds between atoms of different electronegativity. The symmetry of molecules also predicts the polarity of the molecule.

The net dipole moment is shown by adding the vectors of the individual bond dipoles together. The tetrahedral molecules containing polar bonds may or may not be polar depending on their structure. In square planar geometry for the general formula ${\text{CX}}_{\text{2}}{\text{Y}}_{\text{2}}$ (where $\text{X}$ and $\text{Y}$ are either a hydrogen or a halogen atom), there are two isomers possible: cis and trans. In cis isomer, the two halogen atoms would lie on the same side while in trans isomer, the two halogen atoms would lie on the opposite sides.