The theory of resonance in chemistry

The theory of resonance in inorganic and organic chemistry was largely formulated in the period 1927 to 1933 on the basis of the quantum-mechanical theory of the singlet and triplet states of the helium atom that was developed by Heisenberg in 1926 and was given the name quantum-mechanical resonance by him. Some incorrect and seriously misleading remarks about the theory and my part in its development are made in the recently published (1976) Biographical Memoir of Sir Robert Robinson, who in 1926 had made an important contribution to the formulation of the pre-quantum-mechanical electronic theory of the structure and properties of organic molecules. It is pointed out that these remarks have little basis in fact and are based almost entirely on misunderstanding or incompleteness of knowledge of the nature and early history of the theory of resonance.