Question

Question #a162a

Answer 1

Valence bond (VB) theory states that a covalent bond is formed by the overlap of two atomic orbitals.

Explanation:

There are three basic postulates to VB theory.

1. A sigma (σ) bond forms when two orbitals overlap along the internuclear axis.

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A σ bond has the maximum orbital overlap in the region between the two nuclei.

2. A pi (π) bond forms when two atomic orbitals overlap outside of the internuclear axis.

3. The strongest bonds form when there is maximum overlap of orbitals.

Hence, a π bond is weaker than a σ bond.

Modern Valence Bond theory extends these postulates to include the concepts of hybridization (e.g. `sp^3, sp^2, sp`) and resonance.

It cannot predict the shapes of molecules, but we can use it to explain the shapes.