Chapter 9, Problem 9.1DQ

Interpretation Introduction

Interpretation:

The approximations built into valence bond theory and molecular orbital theory has to be listed out and discussed.

Concept introduction:

Valance bond (VBT) theory: This theory explain a chemical bonding theory that explains the bonding between two atoms is caused by the overlap of half-filled atomic orbitals. The two atoms share each other's unpaired electron to form a filled orbital to form a hybrid orbital and bond together.

Molecular orbital (MO) theory: is a method for determining molecular structure in which electrons are not assigned to individual bonds between atoms, but are treated as moving under the influence of the nuclei in the whole molecule.

According to this theory there are two types of orbitals,

1. (1) Bonding orbitals
2. (2) Antibonding orbitals

Electrons in molecules are filled in accordance with the energy; the anti-bonding orbital has more energy than the bonding orbitals.

The electronic configuration of oxygen molecule $O_2$ can be represented as follows,

${\left({\text{σ}}_{\text{1s}}\right)}^2{\left({\text{σ*}}_{\text{1s}}\right)}^2{\left({\text{σ}}_{\text{2s}}\right)}^2{\left({\text{σ*}}_{\text{2s}}\right)}^2{\left({\text{σ}}_{\text{2p}}\right)}^2{\left( {\pi }_{\text{2p}}\right)}^4{\left( \pi {*}_{\text{2p}}\right)}^2 .$

The * represent the antibonding orbital.

Orbital approximation:

It is mainly applied in polyelectron atoms, in this approximation method; hydrogenic orbitals were filled with electron to construct atomic wave functions.