Urey, Harold Clayton (yŏrˈē) [key], 1893–1981, American chemist, b. Walkerton, Ind., grad. Univ. of Montana (B.S., 1917), Ph.D. Univ. of California, 1923. He taught at Johns Hopkins (1924–29), at Columbia (1929–45; as head of the department of chemistry from 1939 to 1942), and at the Univ. of Chicago (1945–58). He became professor-at-large at the Univ. of California in 1958. For his isolation of deuterium (heavy hydrogen) he received the 1934 Nobel Prize in Chemistry; he later isolated heavy isotopes of oxygen, nitrogen, carbon, and sulfur. During World War II, Urey took part in the research leading to the production of the atomic bomb; his special work was on methods of separating uranium isotopes and the production of heavy water. With A. E. Ruark he wrote Atoms, Molecules, and Quanta (1930).