During 1943--1945, the premier physics laboratory in the world was at Los Alamos, but chemistry contributions were vital. Major chemical impacts on the success of the Los Alamos wartime mission included electrochemistry, which found the true melting point of plutonium metal to be hundreds of degrees lower than anticipated. This discovery had profound simplifying effects regarding crucibles to contain molten plutonium and on its production. Other significant chemical contributions involved constant purification of plutonium for reuse, producing carrier-free gamma sources at unprecedented kilo-curie levels, and high polonium work. 8 refs