Question

What are the major drawbacks of valence bond theory?

Answer 1

Hint : The Valence Bond Theory was developed to explain the chemical bonding using the method of quantum mechanics. This theory focuses on the formation of individual bonds from the atomic orbitals of the participating atoms during the formation of a molecule.

Complete Step By Step Answer:
Major drawbacks of valence bond theory are as follows:
The valence bond theory failed to explain carbon's tetra valency.
The energies of the electrons are not discussed.
Electrons are thought to be confined in specific locations.
It does not provide a quantitative assessment of coordination molecules thermodynamic or kinetic stabilities.
There is no distinction between weak and powerful ligands.
The colour that the coordination compound displays is not explained.
Applications of Valence Bond Theory:
The creation of covalent bonds in many molecules can be explained by the maximum overlap requirement stated by the valence bond theory.
One of its most essential applications is the variation in the length and strength of chemical bonds in ${H_2}$ and ${F_2}$ molecules, for example, can be explained by differences in their overlapping orbitals.
An $HF$ covalent bond is a covalent link between two $HF$ molecules.
The Valence Bond theory’s maximum overlap condition can be used to explain how covalent bonds are generated in a variety of compounds. The theory can also provide information on the ionic nature of chemical bonds.

Note :
The ideas of electronic configuration, atomic orbitals (and their overlapping), and atomic orbital hybridization are all included in this theory. Chemical bonds are produced by atomic orbitals overlapping and the electrons being concentrated in the corresponding bond area.