American chemist born in Weymouth, Massachusetts (1875-1946). Lewis's early work, carried out as a faculty member at MIT, involved the determination of electrode potentials of elements, conductivity, and thermodynamics. Most of his later work focused on thermodynamics and chemical equilibrium, electron-pair bonding of atoms and molecules, isotopes, and light-matter interactions. During his 34-year tenure at UC Berkeley, Lewis was renowned as a remarkable teacher and advisor. In 1923 he published Valence and the Structure of Atoms and Molecules, still considered a classic work and a vital contribution to modern bonding theory.