Otto Hahn won the 1944 Nobel Prize in Chemistry for his discovery of the fission of heavy atomic nuclei.
In 1938, Hahn and Fritz Strassmann detected barium after bombarding uranium with neutrons. Hahn recognized that the uranium nucleus had split, while physicists Lise Meitner and Otto Frisch interpreted the process theoretically and named it nuclear fission.
The Nobel citation honored Hahn’s discovery, which is why the prize is often discussed alongside the contributions of Meitner and Frisch. Meitner did not receive a Nobel Prize, a fact that remains a notable episode in the history of nuclear physics.
Nuclear fission releases substantial energy because the products have a slightly lower total mass than the original nucleus. The discovery led to nuclear reactors and, later, nuclear weapons, although Hahn himself opposed the military use of nuclear energy.