How did James Chadwick’s discovery of the neutron help scientists understand nuclear fission?

James Chadwick’s 1932 discovery of the neutron was fundamental to the study of nuclear fission. Because neutrons are electrically uncharged, they can penetrate the atomic nucleus without being deflected by the electrostatic repulsion that affects charged particles. This unique property provided scientists with a powerful tool for inducing atomic disintegration and probing the nucleus.1

Following this discovery, researchers used neutrons to bombard various elements. In 1938, experiments involving the bombardment of uranium with neutrons revealed that the uranium nucleus could split into smaller pieces, such as barium and krypton, releasing significant energy in the process.2

Scientists further determined that the fission process itself generates additional neutrons. This discovery was critical, as it established that if enough material were present, these released neutrons could trigger a self-sustaining chain reaction. This understanding of neutron-induced fission became the scientific basis for both nuclear power and the development of nuclear weapons.23