Selenium attributes

The unusual physical complaints and findings in workers overexposed to teUurium include somnolence, anorexia, nausea, perspiration, a metallic taste in the mouth and garlic-like odor on the breath (48). The unpleasant odor, attributed to the formation of dimethyl teUuride, has not been associated with any adverse health symptoms. Tellurium compounds and metaboUc products have been identified in exhaled breath, sweat, urine, and feces. Elimination is relatively slow and continuous exposure may result in some accumulation. No definite pathological effects have been observed beyond the physical complaints outlined. Unlike selenium, teUurium has not been proved to be an essential biological trace element. 

The stability of this derivative is attributed to the strong mesomeric effect of the NMca group, which changes the nature of the N=S bond. The selenium analogues RNSe have only been detected as transient species. 

In general, it was found that this process is strongly endothermic for sulfur diimides, approximately thermoneutral for selenium diimides and strongly exothermic for tellurium diimides, consistent with experimental observations. These differences can be attributed to the expected trend to lower r-bond energies for chalcogen-nitrogen (np-2p) r-bonds along the series S (n = 3), Se (n = 4) and Te (n = 5). 

Dining attempted conversion of recovered selenium metal to the dioxide by heating in oxygen, a vigorous explosion occurred. This was attributed to selenium-catalysed oxidation of traces of organic impurities in the selenium. Oxidation of recovered selenium with nitric acid is rendered vigorous by presence of organic impurities, but is a safe procedure [1]. The later reference incorrectly attributed the explosions to the nitric acid procedure [2],... 

Aquatic birds nesting at Kesterson Reservoir in 1983 were found to have high rates of embryo deformities and mortality. Beginning in 1984, adult birds were also found dead in unusually high numbers. Through a series of field and laboratory studies, these effects were attributed to the exceptionally high concentrations of selenium in the biogeochemical food web of the birds. 

An endemic disease in China, characterized by loss of hair and nails, skin lesions, and abnormalities of the nervous system, including some paralysis and hemiplegia, was attributed to chronic selenium poisoning. The daily intake for six affected individuals averaged 5.0mg versus 0.1 mg for people from an unaffected area. Changing the diet led to... 

Selenium has many industrial uses, particularly electronic and solid-state applications, which have increased phenomenally in recent years. This is attributed to its unique properties (1) it converts light directly to electricity (photovoltaic action) (2) its electrical resistance decreases with increased illumination (photoconductivity) and (3) it is able to convert alternating current to direct current. 

Another chemist who just missed discovering bromine was J. R. Joss, who in 1824, and again in January, 1826, had recorded in his laboratory notes the appearance of a red color in some hydrochloric acid prepared from gray Hungarian rock salt and Bohemian fuming sulfuric acid. At the time, he attributed this color to the possible presence of selenium from the sulfuric acid. After Balard s discovery, however, he made further experiments with the same materials and became convinced that the red color must be due to bromine. His attempts to obtain more of the bromine-containing rock salt were unsuccessful (147). 

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