Final answer:
Otto Hahn, with his colleague Fritz Strassmann, accidentally discovered nuclear fission in 1938 by identifying barium after bombarding uranium with neutrons, leading to the recognition of a potentially self-sustaining chain reaction.
Step-by-step explanation:
German scientist Otto Hahn, along with his colleague Fritz Strassmann, accidentally discovered nuclear fission in December 1938. While replicating Enrico Fermi's earlier experiments of bombarding uranium with neutrons, they expected to create a heavier element. Instead, they were surprised to identify a much lighter element, barium (Ba-141), as one of the products. This astonishing discovery meant that the uranium nucleus had split into two smaller ones. Furious calculations and verification by Lise Meitner and Otto Frisch confirmed that this was indeed nuclear fission, a process where a heavy atomic nucleus, when hit by a neutron, could be split into two lighter nuclei, releasing a vast amount of energy and further neutrons that could sustain a chain reaction.
German scientist Otto Hahn accidentally discovered nuclear fission in his lab. In December 1938, while experimenting with uranium, Hahn and his colleague Fritz Strassmann found that bombarding uranium with neutrons caused the nucleus to split into smaller nuclei, releasing a large amount of energy. This groundbreaking discovery paved the way for further research in the field of nuclear energy.