Chapter 8, Problem 85A

Interpretation Introduction

Interpretation: Whether the electronegativity difference between two atoms is directly proportional to the strength of the bond or not needs to be explained.

Concept Introduction: A polar covalent bond is formed when two atoms have some electronegativity difference. In this case, the bond is formed by strong electron pairs but the shared pair of electrons is situated more toward the electronegative atom. The more electronegative atom has a partial negative charge and the less electronegative atom has a partial positive charge.

Explanation of Solution

According to the data given in the question, the C-H bond has maximum bond dissociation energy and the C-N bond has minimum bond dissociation energy. Thus, maximum energy is required to break the C-H bond with an electronegativity difference of 0.4 and minimum energy is required to break the C-N bond with an electronegativity difference of 0.5.

Here, the electronegativity difference is minimum for the C-C bond as both C atoms have the same electronegativity value. Also, the difference is the maximum for the C-O bond which is 1.0. For the given statement to be true, maximum energy should be required to break a C-O bond and minimum should be required to break a C-C bond. Since this is not true, the given statement is not valid.

Thus, it is not true that as the electronegativity difference increases, the strength of the bond increases.