Question

What is valence bond theory? How does it differ from the Lewis concept of chemical bonding?

Short answer

Valence bond theory is a quantum physics-based approach to explain chemical bonding and suggests that a bond forms when atomic orbitals overlap and share a pair of electrons. The Lewis concept of bonding is a simpler structural-based theory focusing on valence electrons and the attainment of a stable octet for atoms. In comparison, valence bond theory provides a more detailed and sophisticated description of bonds formation than the Lewis concept.

Step-by-step solution

Presenting the Valence Bond Theory

Valence bond theory is a fundamental theory in quantum chemistry. It proposes that a chemical bond is formed when two atomic orbitals overlap and a pair of electrons is shared between the atoms that the orbitals belong to. In this theory, the strength of a bond depends on the extent of the overlap of the orbitals.

Presenting the Lewis Concept of Chemical Bonding

Lewis concept of chemical bonding or Lewis structures is a simple and generalized view of how atoms form bonds to attain stability. In this concept, atoms are said to be stable when their outermost shell is filled with electrons, typically 8 electrons - conforming to the octet rule. Single, double or triple bonds are shown using lines while lone pairs of electrons are represented as dots.

Comparing Valence Bond Theory to Lewis Concept of Chemical Bonding

While both theories aim to explain chemical bonding, they have different focus points. Lewis theory focuses mainly on the role of valence electrons in the formation of bonds and the attainment of a stable octet. It does not consider the overlapping of atomic orbitals. On the other hand, valence bond theory concentrates more on the nature of wave mechanics in the formation of bonds due to the overlap of atomic orbitals. It's more detailed and complex compared to the Lewis concept.