PTL:Germanium

From ChemEd Collaborative

Germanium

Germanium is a metalloid in Group IVA and in the 4th period. Other members of the group are carbon (C), silicon (Si), tin (Sn), and lead (Pb).

1 Discovered
2 Name
3 Characteristics
4 Found
5 Prepared
6 Uses
7 Emission Spectra

Discovered

The element and its properties were predicted by Mendeleev on the basis of his periodic table of elements. Mendeléev referred to the missing element as eka-silicon. In 1886 Winkler isolated a new element from argyrodite (Ag₈GeS₆), an ore now known to be a double sulfide of silver and germanium. The element is also found in germanite (Cu₂₆Fe₄Ge₄S₃₂), which contains 8% germanium; in zinc ores; in coal; and in other minerals.

Minerals Containing Germanium
Argyrodite

Name

The name is derived from the Latin word, Germania, for Germany and was given to the element by its discoverer, Winkler. The symbol Ge is an abbreviation of the name.

Characteristics

Germanium is a gray-white metalloid, and in its pure state is crystalline and brittle, retaining its luster in air at room temperature.

Found

The element is frequently obtained commercially from flue dusts of smelters processing zinc ores, and it has been recovered from the byproducts of combustion of certain coals. Indeed, its presence in coal insures a large reserve of the element in the years to come.

Prepared

Germanium can be separated from other metals by fractional distillation of its volatile tetrachloride. The tetrachloride may then be hydrolyzed to give germanium dioxide, which can be reduced with hydrogen to give the metal.

GeCl₄(g) + 2 H₂O GeO₂(s) + 4 HCl(g)

Recently developed zone-refining techniques permit the production of germanium of ultrahigh purity.

Uses

Germanium is used as a component in making wide-angle camera lenses as well as in transistors

The element is a very important semi-conductor material. Doped with arsenic or gallium, it is used in transistors and in the construction of rectifiers, photodiodes etc.

Transistors now provide the largest use for the element, but germanium is also finding many other applications including use as an alloying agent, as a phosphor in fluorescent lamps, and as a catalyst.

The element is transparent to the infrared and so is used in infrared spectroscopes and other optical equipment, including extremely sensitive infrared detectors. Its high index of refraction and dispersion has made germanium useful as a component of glass used in wide angle [camera lenses] and microscope objectives.