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43. TechnetiumName: Technetium
Since its discovery, searches for the element technetium in terrestrial materials have been made without success. Technetium has been found in the spectrum of S-, M-, and N-type stars, and its presence in stellar matter is leading to new theories of the production of heavy elements in the stars. Technetium is a silvery-grey metal that tarnishes slowly in moist air. Until 1960, technetium was available only in small amounts. The chemistry of technetium is related to that of rhenium. Technetium (Greek technetos meaning "artificial") was discovered by Carlo Perrier and Emilio Segre in Italy in 1937. The researchers found it in a sample of molybdenum sent to them by Ernest Lawrence. The sample was bombarded by deuterium nuclei in the University of California, Berkeley cyclotron which gave them the isotope Tc-97. Technetium was the first element to be artificially produced. For a number of years there was a gap in the periodic table at element 43. Dmitri Mendeleev predicted that this missing element would be chemically similar to manganese and gave it the name ekamanganese. In 1925 Walter Noddack and Ida Tacke, the discoverers of rhenium, reported the discovery of element 43 and named it masurium, but their report was never confirmed and thus generally accepted as mistaken. (Some chemists have challenged this view.) The development of nuclear energy in the mid 20th century generated the first known samples of element 43 by nuclear reactions. Compounds containing this element are encountered extremely rarely by most people and is for practical purposes not found in nature. Tc-99 is a contamination hazard and should be handled in a glove box. All isotopes of technetium are radioactive. Technetium has no natural biological role. Quick links
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