Tungsten

:This article is about the chemical element. "Tungsten" may also refer to the Tungsten Handheld PDA or to the Tungsten pickups.

Compounds

The most common oxidation state of tungsten is +6, but it exhibits all oxidation states from −2 to +6. Tungsten typically combines with oxygen to form the yellow tungstic oxide, WO3, which dissolves in aqueous alkaline solutions to form tungstate ions, WO42−.

Related Topics:
Oxidation state - Tungstic oxide

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Aqueous polyoxoanions

Aqueous tungstate solutions are noted for the formation of polyoxoanions under neutral and acidic conditions. As tungstate is progressively treated with acid, it first yields the soluble, metastable "paratungstate A" anion, W7O246−, which over hours or days converts to the less soluble "paratungstate B" anion, H2W12O4210−. Further acidification produces the very soluble metatungstate anion, H2W12O406−, after equilibrium is reached. The metatungstate ion exists as a symmetric cluster of twelve tungsten-oxygen octahedra known as the "Keggin" anion. Many other polyoxoanions exist as metastable species. The inclusion of a different atom such as phosphorus in place of the two central hydrogens in metatungstate produces a wide variety of the so-called heteropolyanions.

Related Topics:
Polyoxoanion - Anion - Oxygen - Octahedra - Keggin - Metastable

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