Question

The correct order of increasing bond angles in the following species is

• A. $Cl_2O < ClO_2 < ClO_2^- $
• B. $ClO_2 < Cl_2O < ClO_2^- $
• C. $Cl_2O < ClO_2^- < ClO_2$
• D. $ClO_2^- < Cl_2O < ClO_2 $

Answer 1

The Correct Option is C

To determine the correct order of increasing bond angles among the species Cl_2O, ClO_2, and ClO_2^–, we need to understand the concepts of molecular geometry and the factors affecting bond angles.

Key Concepts:

1. Valence Shell Electron Pair Repulsion (VSEPR) Theory: This theory helps us predict the shape of molecules. The idea is that electron pairs surrounding a central atom tend to repel each other and will, therefore, adopt an arrangement that minimizes this repulsion, leading to a particular molecular geometry.
2. Influence of Lone Pairs and Bond Pairs: Lone pairs of electrons occupy more space than bond pairs, which tends to reduce the bond angles between the bonding pairs.

Analysis:

• Cl_2O: The molecular structure is bent (angular). It has two bond pairs and two lone pairs on the oxygen atom, leading to a bond angle slightly less than the ideal tetrahedral angle of 109.5°, due to lone pair-bond pair repulsion.
• ClO_2: This is a resonance-stabilized radical with one unpaired electron and two double bonds, making the molecular structure bent with a bond angle also less than 120°, but affected by the lone pair as well.
• ClO_2^–: This ion has three lone pairs on chlorine with one being on the terminal oxygen atoms and a formal charge, leading to a slightly decreased bond angle as compared to ClO_2.

Given these configurations, the order of increasing bond angles due to the variance in lone pair repulsion will be:

1. Cl_2O: Presence of lone pairs leads to smaller bond angle compared to others.
2. ClO_2^–: Affects bond angle moderately due to the presence of additional electrons when compared to ClO_2.
3. ClO_2: Highest bond angle amongst the options.

Thus, the correct order of increasing bond angles is: Cl_2O < ClO_2^- < ClO_2.