Question

Valence bond theory of chemical bonding was put forward initially by (a) Heisenberg (b) Einstein (c) Heitler and London (d) dc Broglie

Short answer

(c) Heitler and London

Step-by-step solution

Understand the Question

This question asks for the initial proponents of the valence bond theory in chemistry. The options are Heisenberg (a physicist known for uncertainty principle), Einstein (a physicist known for theories of relativity), Heitler and London (theoretical physicists who applied quantum mechanics to the study of molecular bonds) and de Broglie (a physicist known for wave-particle duality concept).

Recall Relevant Information

From prior knowledge in chemistry, we know that this theory was initially put forward by two physicists named Heitler and London. Their work in the 1920s built the foundation for the valence bond theory.

Confirm Your Answer

Therefore, the correct answer to the question of who initially proposed the valence bond theory is (c) Heitler and London.

Key concepts

Chemical Bonding

Chemical bonding is a central concept in chemistry that explains how atoms connect to form molecules. There are several types of chemical bonds, including ionic, covalent, and metallic bonds, each with unique properties and behaviors. Covalent bonding, in particular, involves the sharing of electron pairs between atoms. The strength and arrangement of these bonds determine the physical and chemical properties of a substance.

Valence bond theory, introduced by Heitler and London, is one of the theories conceptualized to understand these interactions on a deeper level, specifically covalent bonds. It combines principles of quantum mechanics to describe how electron orbitals overlap to create a covalent bond, providing a more nuanced understanding of molecular structure and electron distribution.

Heitler and London

The valence bond theory was initially proposed by two German physicists, Walter Heitler and Fritz London in 1927. They applied the principles of quantum mechanics to the problem of chemical bonding and were the first to give a quantum mechanical explanation of the hydrogen molecule, H₂. Their groundbreaking work illustrated how two hydrogen atom wave functions combine to form a covalent bond.

Heitler and London's approach demonstrated how the spin of electrons and the Pauli exclusion principle play crucial roles in bonding, which paved the way for a more comprehensive theory that addressed the nature of molecular interactions. Their pioneering efforts were critical in the transition from classical to quantum descriptions of chemical bonds, allowing chemists to predict the behavior and properties of molecules with greater accuracy.

Quantum Mechanics in Chemistry

Quantum mechanics is an essential framework in modern chemistry, providing a mathematical explanation for the behavior of particles at the atomic and subatomic levels. It becomes particularly powerful when explaining phenomena where classical physics falls short, such as chemical bonding.

Valence bond theory is a quintessential application of quantum mechanics in chemistry. This theory reconciles the quantum mechanical properties of electrons (like wave-particle duality and quantization) with the observable phenomena of chemical bonds. It explains not just the energy levels that electrons occupy, but also their spatial distribution and how these factors interplay to create stable configurations known as molecules. It's essential for students to understand not only the solutions to problems involving quantum mechanics but also the underlying principles that govern these solutions to truly grasp the wonders of chemistry.