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Tellurium elements

With concentrated nitric acid, selenium and tellurium form only their +4 oxoacids, H2Se03 and H2Te03 respectively, indicating a tendency for the higher oxidation states to become less stable as the atomic number of the element is increased (cf. Group V, Chapter 9). [Pg.267]

Sulphur is less reactive than oxygen but still quite a reactive element and when heated it combines directly with the non-metallic elements, oxygen, hydrogen, the halogens (except iodine), carbon and phosphorus, and also with many metals to give sulphides. Selenium and tellurium are less reactive than sulphur but when heated combine directly with many metals and non-metals. [Pg.268]

Since the hydrogen-element bond energy decreases from sulphur to tellurium they are stronger acids than hydrogen sulphide in aqueous solution but are still classified as weak acids—similar change in acid strength is observed for Group Vll hydrides. [Pg.284]

These closely resemble the corresponding sulphides. The alkali metal selenides and tellurides are colourless solids, and are powerful reducing agents in aqueous solution, being oxidised by air to the elements selenium and tellurium respeetively (cf. the reducing power of the hydrides). [Pg.288]

The elements, sulphur, selenium and tellurium form both di- and tri-oxides. The dioxides reflect the increasing metallic character of... [Pg.288]

Tellurium is occasionally found native, but is more often found as the telluride of gold (calaverite), and combined with other metals. It is recovered commercially from the anode muds that are produced during the electrolytic refining of blister copper. The U.S., Canada, Peru, and Japan are the largest Free World producers of the element. [Pg.120]

Its conductivity increases slightly with exposure to light. It can be doped with silver, copper, gold, tin, or other elements. In air, tellurium burns with a greenish-blue flames, forming the dioxide. Molten tellurium corrodes iron, copper, and stainless steel. [Pg.120]

Gases and vapors of volatile liquids can be introduced directly into a plasma flame for elemental analysis or for isotope ratio measurements. Some elements can be examined by first converting them chemically into volatile forms, as with the formation of hydrides of arsenic and tellurium. It is important that not too much analyte pass into the flame, as the extra material introduced into the plasma can cause it to become unstable or even to go out altogether, thereby compromising accuracy or continuity of measurement. [Pg.102]

Tellurium is not an essential element, and teUurium compounds are in general more toxic than their selenium counterparts. MetaUic teUurium is known to have a teratogenic effect in rats, though no studies have been done on the toxicity of teUurium donor compounds (35). [Pg.242]

Materials for PC Media. Crystalline alloys of elements from the fifth and sixth main group are preferred (3,103,109—111). As the first PC materials, tellurium suboxides as well as Te/Se or Te films that had been doped with small amounts of other elements like Ge, As, or Sb to shift the crystallization point to >100°C have been described. [Pg.149]

Lead Telluride. Lead teUuride [1314-91 -6] PbTe, forms white cubic crystals, mol wt 334.79, sp gr 8.16, and has a hardness of 3 on the Mohs scale. It is very slightly soluble in water, melts at 917°C, and is prepared by melting lead and tellurium together. Lead teUuride has semiconductive and photoconductive properties. It is used in pyrometry, in heat-sensing instmments such as bolometers and infrared spectroscopes (see Infrared technology AND RAMAN SPECTROSCOPY), and in thermoelectric elements to convert heat directly to electricity (33,34,83). Lead teUuride is also used in catalysts for oxygen reduction in fuel ceUs (qv) (84), as cathodes in primary batteries with lithium anodes (85), in electrical contacts for vacuum switches (86), in lead-ion selective electrodes (87), in tunable lasers (qv) (88), and in thermistors (89). [Pg.69]

Mercury Telluride. Compounds of mercury with tellurium have gained importance as semiconductors with appHcations in infrared detection (9) and solar cells (10). The ratio of the components is varied, and other elements such as cadmium, zinc, and indium are added to modify the electronic characteristics. [Pg.114]

Manufacture and Recovery. Electrolytic copper refinery slimes are the principal source of selenium and its sister element, tellurium, atomic numbers 34 and 52, respectively. Electrolytic copper refinery slimes are those constituents in the copper anode which are not solubilized during the refining process and ultimately accumulate in the bottom of the electrorefining tank. These slimes are periodically recovered and processed for their metal values. Slimes generated by the refining of primary copper, copper produced from ores and concentrates, generally contain from 5—25% selenium and 2—10% tellurium. [Pg.327]

Roasting occurs between temperatures of 530—650°C. Virtually no volatilisation of selenium or tellurium takes place during roasting. Conversion of both elements to the hexavalent form is complete. [Pg.328]

It is apparent from these equations that significant quantities of sulfur dioxide are generated. For selenium, the reaction shown for oxidation of elemental selenium reverses itself at the lower temperatures employed for water scmbbing, thus regenerating sulfuric acid. The tellurium dioxide remains in the sulfated slimes. [Pg.329]

The SeBr which forms is distilled from the solution leaving the interfering elements behind. The only other metallic elements that can also distill over by this procedure are arsenic, antimony, tellurium (pardy), and germanium. [Pg.335]

A widely used procedure for determining trace amounts of selenium involves separating selenium from solution by reduction to elemental selenium using tellurium (as a carrier) and hypophosphorous acid as reductant. The precipitated selenium, together with the carrier, are collected by filtration and the filtered soflds examined directly in the wavelength-dispersive x-ray fluorescence spectrometer (70). Numerous spectrophotometric and other methods have been pubHshed for the deterruination of trace amounts of selenium (71—88). [Pg.335]

Nickel—Iron and Cobalt—Iron Alloys. Selenium improves the machinabifity of Ni—Ee and Co—Ee alloys which are used for electrical appfications. Neither sulfur nor tellurium are usefiil additives because these elements cause hot britdeness. The addition of 0.4—0.5% selenium promotes a columnar crystal stmcture on solidification, doubling the coercive force of cobalt—iron-titanium alloy permanent magnets produced with an equiaxial grain stmcture. [Pg.336]

Nitrogen and sodium do not react at any temperature under ordinary circumstances, but are reported to form the nitride or azide under the influence of an electric discharge (14,35). Sodium siHcide, NaSi, has been synthesized from the elements (36,37). When heated together, sodium and phosphoms form sodium phosphide, but in the presence of air with ignition sodium phosphate is formed. Sulfur, selenium, and tellurium form the sulfide, selenide, and teUuride, respectively. In vapor phase, sodium forms haHdes with all halogens (14). At room temperature, chlorine and bromine react rapidly with thin films of sodium (38), whereas fluorine and sodium ignite. Molten sodium ignites in chlorine and bums to sodium chloride (see Sodium COMPOUNDS, SODIUM HALIDES). [Pg.163]


See other pages where Tellurium elements is mentioned: [Pg.600]    [Pg.1102]    [Pg.119]    [Pg.47]    [Pg.600]    [Pg.1102]    [Pg.119]    [Pg.47]    [Pg.89]    [Pg.256]    [Pg.256]    [Pg.319]    [Pg.386]    [Pg.386]    [Pg.3]    [Pg.257]    [Pg.259]    [Pg.289]    [Pg.17]    [Pg.288]    [Pg.193]    [Pg.55]    [Pg.238]    [Pg.474]    [Pg.553]    [Pg.327]    [Pg.327]    [Pg.329]    [Pg.330]    [Pg.332]    [Pg.338]    [Pg.382]    [Pg.124]    [Pg.383]   
See also in sourсe #XX -- [ Pg.238 ]

See also in sourсe #XX -- [ Pg.441 ]




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Elemental tellurium

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