Germanium: the essentials
Germanium is a gray-white semi-metal, and in its pure state is crystalline and brittle, retaining its lustre in air at room temperature. It is a very important semiconductor material. Zone-refining techniques have led to production of crystalline germanium for semiconductor use with an impurity of only one part in 10-10.
Certain germanium compounds have a low mammalian toxicity, but a clear activity against certain bacteria, which makes them of interest as chemotherapeutic agents.
Germanium: historical information
Germanium was an element whose existence was predicted by Mendeleev in 1871. He predicted that the then unknown element germanium should resemble silicon in its properties. He suggested therefore the name ekasilicon (symbol Es). His predictions for the properties of germanium are remarkably close to the reality. Germanium was discovered in a mineral called argyrodite by Clemens Alexander Winkler in 1886.
Germanium: physical properties
Germanium: orbital properties
Isolation: there is normally no need to make germanium in the laboratory as it is readily available commercially. Germanium is available through the treatment of germanium dioxide, GeO2, with carbon or hydrogen. The extraction of germanium from flue dust is complex because of the difficulty in separating it from zinc, which is also present.
GeO2 + 2C → Ge + 2CO
GeO2 + 2H2 → Ge + 2H2O
Very pure germanium can be made by the reaction of GeCl4 with hydrogen.
GeCl4 + 2H2 → Ge + 4HCl