History Of Discovery

Manganese compounds were already used in the Antiquity, but it is difficult to determine the beginning of their usage. Its dioxide, magnesia nigra (MnO₂), was the mineral pyrolusite, sometimes also called simply magnesia or manganese (Origin of Name: from the Latin 'magnes', magnet due to magnetic properties of pyrolusite).

Manganese was recognized as an element (1774) by the Swedish chemist Carl Wilhelm Scheele who investigated chemical properties of the mineral pyrolusite. Manganese was isolated the same year by his associate, Johan Gottlieb Gahn by reduction of the dioxide with carbon.

D.I. Mendeleev predicted existence and properties of technetium (ekamanganese) and rhenium (dvimanganese).

Technetium was detected for the first time in 1937. In the summer of 1936 Emilio G. Segrè (1905-1989), professor of physics at Palermo (Sicily, Italy), visited Berkeley, and saw the new cyclotron laboratory. He became acquainted with Ernest Lawrence and his collaborators McMillan, Abelson, Cooksey, and others. Segrè returned to Palermo with a scrap of radioactive Molybdenum given to him by Lawrence from the Berkeley 27" cyclotron. Together with the professor of mineralogy, Carlo Perrier (1886-1948), he carried out a number of radiochemical experiments on the scrap, which eventuated in the discovery of element No. 43 (Technetium).

Noddack and Tacke at the Physico-Technical Testing Office in Berlin started in 1922 with their attempts to separate elements #43 and #75, first from Platinum ore, but since that was too costly, soon continued with the rare-earth minerals. The X-ray specialist Otto Berg at Werner-Siemens Laboratory did the identification. The team found weak X-ray spectral lines when electrons excited the elements. After three years research, element #75 was separated from columbite, Fe(NbO₃)₂, and named Rhenium (Latin for the River Rhine), after the Rheinland (Rhineland), the homeland of Ida Tacke. About the same time, element #75 was also discovered, independently by the British investigators F.H. Loring and J.F.G. Druce in manganese sulfate, and by the Czechs Jaroslav Heyrovský (1890-1967) and V. Dolejsek.

Дата добавления: 2015-07-25