Question

Discuss the salient features of valence bond theory. What are all its applications?

Short answer

Valence Bond Theory is a fundamental theory that describes covalent bond formation via atomic orbital overlap, differentiating between sigma and pi bonds. It helps understand bond energies, lengths, and angles in molecules. Its main applications include predicting bond strengths and lengths, understanding hybridization, and anticipating molecule shapes.

Step-by-step solution

Understanding Valence Bond Theory

The first step is understanding the Valence Bond Theory. It is a fundamental theory that reveals the electronic structure of molecules. It postulates that a covalent bond is formed between two atoms by the overlap of half-filled valence electronic orbitals, one from each atom. The two electrons (one from each atom) which go into making the bond must have opposite spins. The overlapping of atomic orbitals can be sigma (σ) or pi (π). Sigma bonds are stronger and are formed by head on overlapping, while pi bonds are weaker and result from lateral overlap.

Features of Valence Bond Theory

The second step is defining the main features of the theory. The first key point is the type of bonds: valence bond theory helps explain how they are created through orbital overlap. Secondly, the theory also sheds light on bond energies and bond lengths: higher overlap leads to stronger bonds with more energy and shorter lengths. Thirdly, the theory also highlights bond angles which vary depending on the molecules.

Applications of Valence Bond Theory

The third step is summarising its applications. The valence bond theory offers several applications such as predicting the strengths and lengths of bonds, clarifying the concept of hybridization, understanding the electronic structure of molecules, foreseeing the geometric shape of molecules, and mapping the characteristic properties of molecules.