Gilbert N. Lewis

Gilbert N. Lewis was born on 23 October 1875 in Weymouth, Massachusetts, and died on 23 March 1946 in Berkeley, California. He earned a PhD at Harvard in 1899, taught briefly at MIT, and in 1912 became dean of the College of Chemistry at the University of California, Berkeley, building it into one of the leading chemistry departments in the country. In 1916 he published "The Atom and the Molecule," proposing that a covalent chemical bond consists of a pair of electrons shared between two atoms, and introducing what became known as Lewis structures or Lewis dot diagrams, in which dots placed around an atomic symbol represent its valence electrons and a shared pair drawn between two atoms represents the bond. In 1923 he extended the idea into a general theory of acids and bases, defining an acid as any substance able to accept a shared pair of electrons and a base as one able to donate one, broader than the contemporaneous proton-based Bronsted-Lowry definition and still called Lewis acid-base theory. He also did foundational work in chemical thermodynamics, and in a 1926 letter to Nature coined the word "photon" for the quantum of light. Though nominated for the Nobel Prize in Chemistry repeatedly across three decades, he never won it, one of the field's most discussed omissions; his junior Berkeley colleague Irving Langmuir, who extended and popularized the electron-pair bond during the 1920s, won the 1932 Nobel Prize in Chemistry for related work.