Five Decades Ago: From the “Transuranics” to Nuclear Fission

The discovery of nuclear fission is one of the most outstanding episodes in the history of chemistry: It starts in the spring of 1934 when Enrico Fermi and his group irradiate uranium with neutrons and seem to succeed in going beyond uranium, the then heaviest known element, reaching the first transuranic element; it continues with Otto Hahn, Lise Meitner and Fritz Strassmann who believe to have found additional transuranic elements; with Irène Curie and Paul Savitch who observe an activity which somehow does not fit into that scheme; again with Otto Hahn and Fritz Strassmann who first identify this activity as radium but then on the 17th of December 1938 after rigorous chemical tests realize that the activity is instead barium, thus discovering the fission of the uranium atom into two lighter nuclei; and with Lise Meitner and Otto Robert Frisch who explain nuclear fission on the basis of an already known nuclear model; Otto Robert Frisch finally performs a physical experiment on the 13th of January 1939 which corroborates the fission of uranium. This discovery of nuclear fission is not only an event of historic dimensions, it is also an excellent example of how science evolves, not by successive logical steps but rather through strange detours.