Ida Eva Tacke-Noddack, discovered rhenium and first mentioned the idea of nuclear fission

February 25, 1896, Lakhausen (German Empire) - September 24, 1978, Bad Neuenahr-Ahrweiler (West Germany).

Born Ida Tacke, she was one of the first German women to study chemistry at the Technical University of Charlottenburg in Berlin, where she graduated in 1919. She received her doctorate in 1921, presenting a paper in organic chemistry on ‘Anhydrides of higher aliphatic fatty acids’. She subsequently worked for the companies AEG (1921-23) and Siemens & Halske (1924-25), the first woman to work in German industry.

In 1925, she turned her career to science and began working in the laboratory of the Imperial Institute of Technical Physics, which was headed by Walter Noddack, also a chemist, whom she married in 1926, adopting the surname Noddack.

A year earlier, together with the X-ray expert Otto Berg, they had identified element 75, naming it ‘Rhenium’, from Rhenus, the Latin name for the river Rhine. It is an extremely rare metal in nature (1 gram for every 660 kilos of molybdenum) and is the last element in the table to be found in its natural form. Today, its main deposits are in Chile and Kazakhstan. For this discovery, the couple received the Liebig Medal of the German Chemical Society in 1931.

At the same time, Tacke and Noddack identified another element in the periodic table, number 43, which they called ‘Masurium’, in honour of the German victory over the Russians at the Masurian Lakes. Unable to determine it in successive experiments, the finding remained unconfirmed until 1937, when it was made by the Italians Carlo Perrier and Emilio Segré, who named the element ‘technetium’.

The discovery of these two elements, 43 and 75, filled the gaps left by the Russian Dmitri Mendeleyév, who believed that ‘unknown elements would find their place’, when he proposed the Periodic Table of the Chemical Elements in 1871.

In 1934, a paper by Enrico Fermi was published in Nature, according to which ‘the bombardment of uranium atoms with neutrons produced a radioactive substance’, but the couple published another paper in a Magazine for use in chemistry, with another hypothesis, contrary to Fermi's assertion, in which ‘uranium receiving neutrons could decay into large fragments which would be isotopes of known elements, but not neighbours of the irradiated element’. This was the first prediction of what would later be called nuclear fission, but it was ignored because it implied a great departure from accepted views of nuclear physics and was not supported by any theory to explain it. Years later, in 1939, research by Otto Hahn, Fritz Strassmann, and Lise Meitner would prove Tacke-Noddack right, so it is undeniable that the idea of nuclear fission was his.

In the same article, they put forward another hypothesis, which was also ignored, stating that the periodic system could provide discoveries beyond the chemical elements, with more information about the structure of matter; in particular, about a possible classification system based on a table of isotopes and not just elements. According to his hypothesis, the nucleus forms layers with increasing atomic numbers, similar to the electron configuration. Research would have to focus on the nuclei of each isotope and not just on the electrons of the elements.

In 1935, the couple moved to the Physico-Chemical Institute of the University of Freiburg (Germany), where she worked as a research associate, until 1941 when they moved to the French University of Strasbourg, a city then occupied by Germany. When Strasbourg returned to French control in 1944, they returned to Germany, and after the end of World War II, they settled for several years in Turkey.

In 1956, they returned home to work at the State Institute for Geochemical Research in Bamberg. After her widowhood on 7 December 1960, she remained in Bamberg until 1968, when she retired.

In addition to the Liebig Medal, she was awarded the Scheel Medal of the Swedish Chemical Society (1934), an honorary doctorate from the University of Hamburg, and the Cross of Merit of the Federal Republic of Germany (both in 1966). Together with her husband, she was nominated three times for the Nobel Prize in Chemistry (1933, 1935, and 1937).