Otto Berg (chemical) – Wikipedia, free encyclopedia

Otto Carl Berg (1873 – 1939) was a German physical chemist and one of the scientists attributed to the discovery of Renio, along with Ida Tacke -Noddack and Walter Noddack. The Renio was the following element to the last discovered of natural origin, asceose the last element that was discovered that it has a stable isotope. They are not officially recognized the discovery of element 43, which the research team called at that time with the name of Masurio. ^{[ first ]} ​

Between 1894 and 1898 he studied Chemistry in Berlin, Heidelberg and Brisgovia Freburg. In the 1902-1911 period he worked as a professor at Greifswald. Subsequently, he joined Siemens & Halske in Charlottenburg. ^{[ 2 ]} ​

As X -ray specialist, he collaborated with Walter Noddack and Ida Tacke to find the latest unknown elements of nature with atomic numbers 43 and 75. In 1925 the team achieved the discovery of the two, whom they gave the names of Renio and Masurio . The Renio (Z = 75) was detected in the X -ray spectra, and came to isolate 1 gram from mineral samples. ^{[ 3 ]} Although X -ray tests demonstrated the safe presence of the Masurio element in 28 of the 1000 spectra, and a probable presence in another 70 cases, the demonstrations of Noddack, Tacke and Berg could not be reproduced, nor could it be isolated the element. ^{[ 4 ]} ​

During 1925 in Germany, scientists Walter Noddack, Ida Tacke and Otto Berg reported that they had detected the chemical element of atomic number 75 in a platinum mineral and in the Columbita mineral. They also found Renio in La Gadolinita and Molibdenite. ^{[ 5 ]} During 1928 they were able to extract a gram of the Renio element from the transformation of 660 kg of molybdenite. ^{[ 6 ]} ​

The same team was also involved in the discovery of Tecnecio. In 1925 they informed about the discovery of the elements of atomic number 75 and 43: to this last element (Z = 43) called Masurio (by the Masuria region, then in Eastern Prussia, currently in Poland, the region where it was originally Walter Noddack family). ^{[ 7 ]} The group of researchers bombarded the columbita with an electron beam and deduced the presence of element 43 by examining X -ray diffraction spectrograms. The wavelength of the X -rays produced is related to the atomic number by a deduced formula By Henry Moseley. The team claimed the detection of a weak X -ray signal in a wavelength produced by element 43. Contemporary experimenters could not repeat the discovery, and in fact it was considered as an error for many years. ^{[ 8 ]} ​

It was not until 1998 when this dismissal began to be questioned. John T. Armstrong, of the National Institute of Standards and Technology (NIST) executed simulations on the computer of the experiments and obtained results very similar to those reported by the 1925 team. That claim was backed by the work published by David Curtis of the National Laboratory The poplars measuring the (small) natural appearance of the Tecnecio. ^{[ 9 ]} The experimental results of Berg and the Noddack have never reproduced, and were not able to isolate any amount of element 43. The debate persists on whether the 1925 team actually discovered element 43. An extension on this controversy can be found A section of the Ida Noddack article.

The discovery of element 43 was finally confirmed by an experiment of 1937 in Sicily, finally recognized to Emilio Segre and Carlo Perrier, who gave him the name of Tecnecio. At the IUPAC conference of 1949, this name was officially established.

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