Germanium

Germanium - Ge

CAS: 7440-56-4
Description: Hard brittle grayish-white metal
Classification: Metalloid
Date of Discovery: 1886
Discoverer: Clemens Winkler
Name Origin: Latin Germania, "Germany"

Atomic Number: 32
Number of Neutrons: 41
Atomic Mass: 72.61(2) amu
Melting Point: 938.25 °C
Boiling Point: 2833 °C
Density (293 K): 5.323 g/cm³
Atomic volume: 13.6 cm³/mol
Electrical resistivity: 1.45e^-8 10^-6/cm

Thermal conductivity: 0.599 W/cmK
Enthalpy of atomization: 376.56 kJ/mol
Enthalpy of vaporization: 330.90 kJ/mol
Enthalpy of fusion: 36.940 kJ/mol
Specific heat capacity: 0.32 J/gK

Energy levels: 2-8-18-4
Electron configuration: [Ar]3d¹⁰4s²4p²
Crystal Structure: Cubic face centered
Atomic radius: 1.52 Å
Covalent radius: 1.22 Å
Oxidation States: +2, +4
Electronegativity, Pauling: 1.61
Electron affinity: 1.233 eV
First ionization energy: 7.899 eV
2nd ionization energy: 15.934 eV
3rd ionization energy: 34.22 eV
Polarizability: 6.07 10^-24cm³

Isotope	Natural Abundance	Atomic Mass	Half-life	Decay Mode	Spin
⁶¹Ge	60.9638	0.04 s	⁺
⁶³Ge	62.9496	0.10 s	^-
⁶⁴Ge	63.9416	1.06 m	⁺; EC	0+
⁶⁵Ge	64.9394	31 s	⁺; EC
⁶⁶Ge	65.93385	2.26 h	⁺; EC	0+
⁶⁷Ge	66.932738	19.0 m	⁺; EC	1/2-
⁶⁸Ge	67.92810	270.8 d	EC	0+
⁶⁹Ge	68.927973	1.63 d	⁺; EC	5/2-
⁷⁰Ge	21.23(4)	69.924250	Stable	0+
^71mGe	20.4 ms	IT	9/2+
⁷¹Ge	70.924954	11.2 d	EC	1/2-
⁷²Ge	27.66(3)	71.922076	Stable	0+
⁷³Ge	7.73(1)	72.923460	Stable	9/2+
⁷⁴Ge	35.94(2)	73.921178	Stable	0+
^75mGe	48 s	IT	7/2+
⁷⁵Ge	74.922860	1.380 h	^-	1/2-
⁷⁶Ge	7.44(2)	75.921403	Stable	0+
^77mGe	53 s	IT; ^-	1/2-
⁷⁷Ge	76.923549	11.30 h	^-	7/2+
⁷⁸Ge	77.922853	1.45 h	^-	0+
^79mGe	39 s	^-; IT	7/2+
⁷⁹Ge	78.9254	19.1	^-	1/2-
⁸⁰Ge	79.92545	29.5 s	^-	0+
^81mGe	7.6 s	^-	1/2+
⁸¹Ge	80.9288	7.6 s	^-	9/2+
⁸²Ge	81.9296	4.6 s	^-	0+
⁸³Ge	82.9345	1.9 s	^-
⁸⁴Ge	83.9373	0.98 s	^-
⁸⁵Ge	83.943	0.54 s	^-
Predicted by Mendeleev in 1871 as ekasilicon, and discovered by Winkler in 1886. The metal is found in argyrodite (Ag₈GeS₆); in germanite (Cu₂₆Fe₄Ge₄S₃₂), which containes 8% of the element; in zinc ores; in coal; and in other minerals. The element is frequently obtained commercially from the dusts of smelters procesing 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 element 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; the dioxide can then be reduced 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 one part in 10¹⁰. Doped with arsenic, gallium, or other elements, it is used as a transistor element in thousands of electronic applications. Its applicaion as a semiconductor element now provides the largest use for germanium. Germanium is also finding many other applications including use as an alloying agent, as a phosphor in fluorescent lamps, and as a catalyst. Germanium and germanium oxide are transparent to the infrared and are used in infrared spectroscopes and other optical equipment, including extremely sensitive infrared detectors. Germanium oxide's high index of refraction and dispersion has made it useful as a component of glasses used in wide-angle camera lenses and microscope objectives. The field of organogermanium chemistry is becoming increasingly important. Certain germanium compounds have a low mammalian toxicity, but a marked activity against certain bacteria, which makes them of interest as chemotherapeutic agents. Twenty-nine isotopes and isomers are known, five of which occur naturally. LINKS: AMM Online - Germanium Profile Germanium and Indium Modeling Germanium Comes of Age High Purity Germanium Crystals IBM Introduces First Mainstream Silicon Germanium Chips Silicon Germanium (SiGe) Research in the Cavendish Laboratory Return Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998.

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