Chemical Properities

At temperature 250 °C, germanium slowly oxidizes to GeO₂. Germanium dissolves slowly in concentrated sulfuric acid, and is insoluble in diluted acids and alkalis. It will react violently with molten alkalis to produce [GeO₃]^2-. The common oxidation state that Germanium occurs in is +4 and +2. Under rare conditions, Germanium also occurs in oxidation states of +3, +1, and -4.

There are two forms of oxides of germanium, germanium dioxide (GeO₂) and germanium monoxide (GeO). By roasting germanium sulfide, germanium dioxide can be obtained. As for germanium monoxide, it can be obtained by the high temperature reaction of germanium dioxide and germanium metal. Germanium dioxide has the unusual property of refractive index for light but transparency to infrared light.