1893-1970

British chemist who applied quantum theory to explain organic chemical reactions as the breaking and formation of bonds resulting from the rearrangement of bonding electrons. Ingold proposed that dipoles (separation of charge centers) in molecules may be either permanent (due to the structure of the molecules) or temporary (caused by an external polarizing agent). He also defined reactants as nucleophilic if they give up electrons in a reaction, and electrophilic if they accept electrons.