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Definition: tellurium from The Penguin Dictionary of Science

Symbol Te. The element with atomic number 52 and relative atomic mass 127.6, which is in Group 16 of the ➤periodic table below selenium (their names are connected as selenium comes from ‘Moon’ and tellurium from ‘Earth’). It is best classified as a ➤metalloid, the grey allotrope having a low electrical conductivity. Cationic clusters, such as the bright-red species Te42+, also exist. Its chemistry resembles that of sulfur, with a similar range of oxidation numbers: -2, +2, +4 and +6 being most common. One infamous compound is hydrogen telluride, a gas with at least as revolting a smell as that of hydrogen sulfide, but which suffers from the disadvantage that it is absorbed by the skin causing the unpleasant odour to persist longer.

Summary Article: tellurium
from The Columbia Encyclopedia

(tĕlʊr'ēӘm) [Lat.,=earth], semimetallic chemical element; symbol Te; at. no. 52; at. wt. 127.60; m.p. 450 degrees Celsius; b.p. 990 degrees Celsius; sp. gr. 6.24 at 20 degrees Celsius; valence −2, +4, or +6. Tellurium is a lustrous, brittle, crystalline, silver-white metalloid. A powdery brown form of the element is also known. Tellurium forms many compounds corresponding to those of sulfur and selenium, the elements above it in Group 16 of the periodic table. The dioxide, TeO2, is formed when the element is burned in air. Tellurium forms two weak acids and a number of halogen compounds. With hydrogen and with some metals it forms tellurides. Tellurium and its compounds are probably poisonous. Tellurium is occasionally found uncombined in nature but is more often found combined with metals, as in the minerals calaverite (gold telluride) and sylvanite (silver-gold telluride). Tellurium is recovered as a byproduct of the electrolytic refining of blister copper. It is used as an additive to steel and is often alloyed with aluminum, copper, lead, or tin. It is used in vulcanizing rubber, as a coloring agent in glass and ceramics, and in catalysts for petroleum cracking. Tellurium is a semiconductor material and is slightly photosensitive. It is used with bismuth in thermoelectric devices. Tellurium was discovered in 1782 by Franz Muller von Reichenstein. It was named by M. H. Klaproth, who isolated it in 1798.

The Columbia Encyclopedia, © Columbia University Press 2018

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