Chapter 7, Problem 7.1VC

Interpretation Introduction

Interpretation:

From the options given below, the one that best describes the difference between sigma bond and pi bond has to be identified.

1. (a) A sigma bond is a bonding molecular orbital; a pi bond is an anti-bonding molecular orbital.

1. (b) A sigma bond is a single bond whereas a pi bond is a double bond.

1. (c) The electron density in the sigma bond lies along the internuclear axis; that of a pi bond doesn’t.

Concept Introduction:

Hybridization is a hypothetical concept.  It refers to overlapping of atomic orbitals and the resultant orbitals formed are known as hybrid orbitals. After hybridization, the orbitals cannot be distinguished individually.  The orientation of the orbitals while overlapping impacts the nature of the bond forms.

A bond between two atoms is known as sigma bond if the atomic orbitals of the atoms overlap end to end – it is also called head on overlapping.  A bond is said to pi bond if it is formed by sideways overlapping of atomic orbitals of the atoms.

Correct answer:

The option (c) – “The electron density in the sigma bond lies along the internuclear axis; that of a pi bond doesn’t” best describes the difference between sigma bond and pi bond.

Reason for correct option:

In sigma bond formation, the head on overlapping of atomic orbitals causes electron density to be cylindrically symmetrical about inter-nuclear axis.