![]() ![]() Meitner was a physicist who had recently fled to Sweden to escape the Nazi regime. Hahn then turned to his colleague, Lise Meitner, for an explanation. ![]() They reported their results as follows: "As chemists, we must actually say the new particles do not behave like radium but, in fact, like barium as nuclear physicists, we cannot make this conclusion, which is in conflict with all experience in nuclear physics." Hahn, the chemist, was reluctant to go against the ideas of respected nuclear physicists, despite clear chemical evidence of barium. ![]() Hahn and Strassmann repeated the experiment numerous times and were never able to isolate the ‘radium’ from barium. Hahn and Strassmann’s laboratory apparatus Could Ida Noddack’s hypothesis be correct? Had the uranium atoms split into fragments of approximately equal mass? Hahn and Strassmann were unable to separate the radioactivity of the 'Ra' from that of the barium fractions and thus confirmed that one of the products of neutron bombardment of uranium was not neighboring radium, but distant barium. The final step in this procedure was a fractional crystallization to separate the barium carrier from the suspected 'radium'. Since radium and barium are group IIA elements, having the same chemical properties, barium was added as a carrier to facilitate the chemical isolation of the small amounts of the suspected 'radium'. (The chemical separation is shown below.) The suspected radioisotope of 'radium' is indicated as 'Ra'. To be absolutely certain, Hahn and Strassmann decided to identify the ‘radium’ isotopes by chemical means. Presumably, isotopes of radium produced by the initial neutron bombardment of uranium decayed to thorium and actinium. Lise Meitner and Otto Hahn (Courtesy of the American Institute of Physics)Įarly in December 1938, Hahn and Strassmann thought that they had established the nuclear reactions that yielded the products observed by the Joliot-Curies. ![]()
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