Germanium (Ge) is a gray-white metalloid element of group IVA of the period table. Germanium takes the form of a brittle crystalline solid whose structure resembles that of diamond. It occurs naturally in sulfide ores of silver, copper, and zinc, and in certain coals, and is extracted as a by-product of processing them. It is important in transistors, rectifiers, and other similar semiconductor devices, and is also used in alloys and for lenses and windows for infrared radiation.

 

The chemical properties of germanium are intermediate between those of silicon and tin; it reacts with the halogens, oxidizes in air at 600°C, and is attacked by concentrated oxidizing acids and by fused alkalis. It forms covalent tetra- and divalent compounds (see below). Its most common isotope is ⁷⁴Ge (36.54%).

The existence of an element with the properties of germanium was predicted in 1871 by the Russian chemist Dmitri Mendeleyev. He called it eka-silicium, from silicium (the old name for silicon) and the Sanskrit word eka meaning 'one'. Germanium was discovered in 1886, 15 years after he had made his prediction.

 

atomic number	32
relative atomic mass	72.59
electron configuration	1s22s22p63s23p63d104s24p2
relative density	5.35
melting point	937°C (1,719°F)
boiling point	2,830°C (5,126°F)

 

Compounds of germanium

Germanium (IV) oxide (GeO₂) is used in high-refractive-index glass. Melting point 1,086°C.

 

Germanium (IV) chloride (GeCl₄) is a colorless liquid intermediate in the extraction of germanium and the preparation of most of its compounds. Melting point –50°C, boiling point 84°C.

 

The germanes are a series of volatile hydrides resembling the silanes.