Tungsten chemical properties

Chromium, molybdenum and tungsten thermodynamic properties, chemical equilibria and standard potentials. I. Dellien, F. M. Hall and L. G. Hepler, Chem. Rev., 1976, 76, 283-310 (400). 

There are undoubtedly more elements on the way, as little by little the Periodic Table is extended into uncharted waters. And as this happens, we will learn about how these new elements behave. In 1997 an international team that included scientists from GSI, Berkeley, and Dubna was able to deduce that element 106 (seaborgium) has chemical properties similar to molybdenum and tungsten. In a sense this might have been expected, since seaborgium sits below these elements in the Periodic Table. But in fact the result was a surprise, because the chemical behaviour of the preceeding superheavy elements 104 and 105 is distorted by the effects of relativity on the electrons surrounding the immense nuclei. 

The physical-chemical properties of a synthetic gallophosphate molecular sieve, the 30-A supercage cloverite , have been assessed [18]. Instead of attempting to list the burgeoning number of fullerene publications, attention is drawn to the formation and characterization of fullerene-like nanocrystals of tungsten disulfide [19,20]. Preparation, characterization and utilization of carbon nanotubes have been the subject of a number of reports from several laboratories [21-27]. 

Tungsten-based catalysts with a Lewis base promoter are used in the polymerization of dicyclopentadiene also isolated from the C5 stream-cracker fraction.150,155 The product poly(dicyclopentadiene) or Metton resin has unusual physical and chemical properties. It is processed together with elastomers to increase viscosity of the end product by using reaction injection molding (RIM) technology.155... 

The thin yellow flakes of tungsten(VI) dichloride dioxide, and the compounds to be mentioned later as well, are sensitive to atmospheric moisture. Therefore the reaction tubes must be opened in a dry nitrogen atmosphere and stored either under vacuum or in a dry inert gas. The detailed physical and chemical properties of tungsten(VI) dichloride dioxide are described in the literature.1... 

The chemical properties of tungsten are similar to those of molybdenum tungsten is more expensive, however, and its industrial use is therefore limited. Especially when hydrogenation is carried out under severe conditions, such as in hydrocracking, sulfided Ni-W/A Os catalysts have advantages over sulfided Ni-Mo/Al203. 

The GD plasma environment is an interesting vessel to study gas-phase chemical properties. The gettering qualities of carbon, silver, tantalum, titanium, and tungsten were compared by Mei and Harrison [40] on the basis of the atomic ion fraction of all of the observed lanthanum species R = La+/(La+ + LaO+) X... 

The crystal structures adopted by the binary carbides and nitrides are similar to those found in noble metals. The resemblance is not coincidental, and has been explained using Engel-Brewer valence bond theory [5]. Briefly, the main group elements C and N increase the metal s effective s-p electron count, so that structures and chemical properties of the early transition metals resemble those of the Group 8 metals. This idea was first introduced by Levy and Boudart [6] who noted that tungsten carbide had platinum-like properties. 

Another effect of lanthanide contraction is that the third row of the d-block elements have only marginally larger atomic radii than the second transition series. For example, zirconium and hafnium, niobium and tantalum, or tungsten and molybdenum have similar ionic radii and chemical properties (Zr + 80 pm, Hf + 81 pm Nb + 70 pm, Ta + 73 pm Mo + 62 pm, W + 65 pm). These elements are also found in the same natural minerals and are difficult to separate. 

Element 106. The chemical properties of element 106 (eka-tungsten) are predicted to be similar to those of tungsten, molybdenum and to some extent chromium, offering an even richer chemistry of complex ions than these elements. The hexafluoride should be quite volatile and the hexachloride, pentachloride and oxychloride should be moderately volatile. Penneman and Mann predict a -)-4 oxidation state in aqueous solution. Jprgensen s selection of k is for the hydrated cation and is not intended to account for the effects of complex ion formation. However, since tungsten is stabilized in the oxidation state of -t-6 by the tungstate ion, an analogous situation may be expected for element 106. 

Tungsten Trisilicide, WS%, was isolated by Frilley from a mi.xed iron tungsten silicide containing 9 per cent, iron, 51-6 per cent, tungsten, and 38-4 per cent, silicon by successive treatment with concentrated hydrofluoric acid, hot concentrated sodium liydroxide, and dilute hydrofluoric acid. The crystals obtained were white and lustrous, and exhibited similar chemical properties to those of the disilicide. 

Occurrence—History—Preparation —Tungsten Pilanieiits—Physical Properties —Spectrum—Chemical Properties—Atomic Weight—Uses—Alloys. 

In addition, some physical and chemical properties of tungsten will... 

The electron configuration, especially the 5(1 niveaus, is responsible for the typical tungsten-related physical and chemical properties. 

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