Element Tellurium, Te, Metalloid
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Tellurium History
Tellurium had been discovered when analytical chemistry began flourishing in the second half of 18th century. A new gold-containing ore had been found in Siebenburgen (Transylvania). Franz-Joseph Muller (later baron von Reichenstein), chief inspector of mines in Siebenburgen, analyzed the ore and extracted from it a substance considered that time as a new metal. Muller sent samples to Torbern Bergman, the Swedish chemist-analyst for further analysis, but Bergman died before he could do further analysis. In the meantime Paul Kitaibel, the Hungarian professor of botany and chemistry, in 1789 had extracted some unknown, as he reckoned, metal (actually metalloid) from wehrlit. Kitaibel provided the detailed description of new-discovered element; however he did not report about his discovery, just sent letters to some scientists. One of them was received by F.J.A. Estner, a mineralogist from Vienna, and he informed Klaproth about it, Martin Heinrich Klaproth (1743-1817). He succeeded and confirmed the discovery of the new metal. In his paper before the Academy of Sciences of Berlin of 25 January 1798 he gave the metal the "von der alten Mutter Erde entlehnten" name Tellurium that derives of Latin tellus = Earth.
Tellurium Occurrence
Tellurium is present in the Earth's crust at an average concentration of only about 1 x 10-7% by mass. It is a constituent part of 100 minerals including native Tellurium, altaite (lead telluride) PbTe, and hessite (telluric silver) Ag2Te, sylvanite AuAgTe4, calaverite AuTe2, tetradymite (bismuth telluride) Bi2Te2S. As an isomorphous mixture tellurium is found in chalcopyrite, galena, pyrite and pentlandite. Tellurium may be recovered from copper, lead and pyrite ores in which it is dispersed as a trace element or as microinclusions of its own minerals. Some of tellurium own minerals also may contain gold which, however, does not have any commercial significant.
Tellurium is permanently present in plant and animal tissues. An average concentration in plants growing on tellurium-rich soils reaches 2x10-4-2.5x10-3%, in terrestrial animal organisms - 2x10-6%. Daily supply with food and water is 0.6 mg. Tellurium is moderately toxic for plants and highly poisonous for mammals: it may cause inhibition of growth, fall-off, paralysis and so forth).
Tellurium Neighbours
Elements Periodic Table |