Chapter 7, Problem 7.15QP

Interpretation Introduction

Interpretation:

From the given set of options the one which is showing incorrect deviation in the bond angle has to be found.

Concept Introduction:

$VSEPR$ theory $(Valanceshellelectronpairreplusiontheary)$ is an important theory in chemistry which is useful in predicting the structure of a molecule.  According to this theory, the shape of the molecules depends upon the number of electrons around the central atoms.  The valance electrons in an atom will repel each other.  The molecule will adopt a structure in such a way that the electronic repulsion is minimised.

According to $VSEPR$ theory,

• When two bond pairs of electrons are present the molecule will have a linear structure of bond angle $180°$
• When three bond pairs of electrons are present the molecule will have a trigonal planar structure of bond angle $120°$
• When for bond pairs of electrons are present the molecule will have a tetrahedral structure of bond angle $109.5°$
• When five bond pairs of electrons are present the molecule will have a trigonal bi-pyramidal structure of bond angles $90°$ and $120°$
• When six bond pairs of electrons are present the molecule will have a octahedral structure of bond angle $90°$
• When seven bond pairs of electrons are present the molecule will have a pentagonal bi-pyramidal structure of bond angles $90°$ and $72°$

When lone pairs of electrons are present there will be a deviation from the ideal structure, as the repulsion between lone pairs of electrons are more than that of bond pairs.