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GeGe at. wt. 72.59 at. no. 32 m.p. 937.4°C b.p. 2830°C sp. gr. 5.323 (25°C) solid sp. gr. 6.095 (29.8°C) liquid valence 2 and 4.
| SHELL | K | L | M | N | O | P | Q |
| SUB SHELL | He | Neon | Argon | Krypton | Xenon | Radon | Eka-radon |
| 1s | 2s 2p | 3s 3p | 3d 4s 4p | 4d 5s 5p | 4f 5d 6s 6p | 5f 6d 7s 7p | |
| Germanium | 1s22s22p63s23p63d104s24p2 | ||||||
| Symbol | 3P0 | ||||||
Germanium was predicted by Mendeleev in 1871 as ekasilicon, and discovered by Winkler in 1886. The metal is found in argyrbdite, a sulfide of germanium and silver; in germanite, which contains 8 % of the element; in zinc ores; in coal; and in other minerals. The element is frequently obtained commercially from flue dusts of smelters processing zinc ores, and has been recovered from the by-products of combustion of certain coals. Its presence in coal insures a large reserve of the elernent in the years to come. Germanium can be separated from other metals by fractional distillation of its volatile tetrachloride. The tetrachloride may then be hydrolyzed to give Geo2; then the dioxide can be reduced with hydrogen to give the metal. Recently developed zone- refining techniques permit the production of germanium of ultra-high purity. The element is a gray-white metalloid, and in its pUre state is crystalline and brittle, retaining its luster 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 I part in 1010. Doped with arsenic, gallium or other elements, it is used as a transistor element in thousands of electronic applications. 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. Germanium oxide is transparent to the infrared and is used in infrared spectroscopes and other 'optical equipment, including extremely sensitive infrared detectors. Its high index of refraction and dispersion has made ger- manium useful as a component of glasses used in wide' angle camera lenses and microscope objectives. The field of organogermanium chemistry is becoming increasingly im- portant. Certain germanium' compounds have a low mammalian toxicity, but a marked activity against certain bacteria, which makes them of interest as chemotherapeutic agents. The cost of getmanium is about 50 cents/gm. for 99.9 + % purity in small lots.
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