Lapworth, Arthur (1872–1941)

British chemist, one of the founders of modern physical-organic chemistry. He formulated the electronic theory of organic reactions (independently of English chemist Robert Robinson).

Lapworth was one of the first to emphasize that organic compounds can ionize, and that different parts of an organic molecule behave as though they bear electrical charges, either permanently or at the moment of reaction.

With the development of theories of valency based on the electronic structure of the atom, Lapworth was able to refine some speculations about ‘alternative polarities’ in organic compounds into a classification of reaction centres as either ‘anionoid’ (nucleophilic) or ‘cationoid’ (electrophilic), the changes being determined by the influence of a key atom such as oxygen.

Lapworth was born in Galashiels, Scotland, and studied at Mason College, Birmingham. He became head of the chemistry department at Goldsmiths' College, London, in 1900. In 1909 he moved to Manchester, where he remained, becoming professor 1922.