All practice pages/Interatomic theory/Elements
Element 32, a metalloid
The metalloid Mendeleev called eka-silicon, and the material of the very first transistor.
Period 4, group 14. The other metalloids are tinted, and every cell opens its own article.
Four valence electrons, like carbon and silicon. Germanium shares them in four covalent bonds, and in the pure crystal that arrangement makes it a semiconductor.
Rare and spread thin. It is recovered as a byproduct of zinc refining and from the ash of certain coals, mainly in China.
Clemens Winkler found it in 1886 in argyrodite, a silver mineral from Saxony, and named it after his homeland, Germany. Its atomic mass, density and oxide matched Mendeleev's 1871 predictions for eka-silicon almost exactly.
Fiber-optic cables, whose glass cores contain germanium dioxide; lenses and windows for infrared cameras and night vision; and high-efficiency solar cells for satellites. The first transistor, built at Bell Labs in 1947, was made of germanium.