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Gallium - Germanium - Arsenic
Name, Symbol, NumberGermanium, Ge, 32
Series Metalloids
Group, Period, Block14 (IVA)[?], 4 , p
Density, Hardness 5323 kg/m3, 6
Appearance greyish white
Atomic Properties
Atomic weight 72.64 amu
Atomic radius (calc.) 125 (125) pm
Covalent radius 122 pm
van der Waals radius no data
Electron configuration [Ar]3d10 4s2 4p2
e- 's per energy level2, 8, 18, 4
Oxidation states (Oxide) 4 (amphoteric)
Crystal structure Cubic face centered
Physical Properties
State of matter solid
Melting point 1211.4 K (1720.9 F)
Boiling point 3093 K (5108 F)
Molar volume 13.63 ×10-3 m3/mol
Heat of vaporization 330.9 kJ/mol
Heat of fusion 36.94 kJ/mol
Vapor pressure 0.0000746 Pa at 1210 K
Speed of sound 5400 m/s at 293.15 K
Electronegativity 2.01 (Pauling scale)
Specific heat capacity 320 J/(kg*K)
Electrical conductivity 1.45 ohm
Thermal conductivity 59.9 W/(m*K)
1st ionization potential 762 kJ/mol
2nd ionization potential 1537.5 kJ/mol
3rd ionization potential 3302.1 kJ/mol
4th ionization potential 4411 kJ/mol
5th ionization potential 9020 kJ/mol
Most Stable Isotopes
isoNAhalf-life DMDE MeVDP
70Ge21.23%Ge is stable with 38 neutrons
72Ge27.66%Ge is stable with 40 neutrons
73Ge7.73%Ge is stable with 41 neutrons
74Ge35.94%Ge is stable with 42 neutrons
SI units & STP are used except where noted.
Germanium is a chemical element in the periodic table that has the symbol Ge and atomic number 32. This is a lustrous, hard, silver-white, metalloid that is chemically similar to tin. Germanium forms a large number of organometallic compounds and is an important semiconductor material used in transistors and photodetectors[?].

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Notable Characteristics Germanium is a hard, grayish-white element that has a metallic luster and the same crystal structure as diamond. In addition, it is important to note that germanium is a semiconductor, with electrical properties between those of a metal and an insulator. In its pure state, this metalloid is crystalline, brittle and retains its luster in air at room temperature. Zone-refining techniques have led to the production of crystalline germanium for semiconductors that have an impurity of only one part in 1010. Applications Unlike most semiconductors, germanium has a small band gap, allowing it to efficiently respond to infrared light. It is therefore used in infrared spectroscopes and other optical equipment which includes extremely sensitive infrared detectors. Its oxide's index of refraction and dispersion properties make germanium useful in wide-angle camera lenses and in microscope objective lenses.

The alloy silicon germanide[?] (SiGe) is rapidly becoming an important semiconductor material, for use in high speed integrated circuits. Circuits utilising the properties of Si-SiGe junctions can be much faster than those using silicon alone.

Other uses:

Certain compounds of germanium have low toxicity to mammals, but have toxic effects against certain bacteria. This property makes these compounds useful as chemotherapeutic agents. History In 1871 germanium (Latin Germania for Germany) was one of the elements that Dmitri Mendeleev predicted to exist as a missing analogue of the silicon group (Mendeleev called it "ekasilicon"). The existence of this element was proven by Clemens Winkler[?] in 1886. This discovery was an important confirmation of Mendeleev's idea of element periodicity.

Property Ekasilicon Germanium
atomic mass 72 72.59
density (g/cm3) 5.5 5.35
melting point (°C) high 947
color gray gray

The development of the germanium transistor opened the door to countless applications of solid-state[?] electronics. From 1950 through the early 1970s, this area provided an increasing market for germanium, but then high purity silicon began replacing germanium in transistors, diodes, and rectifiers. Silicon has superior electrical properties, but requires much higher purity samples—a purity which could not be commercially achieved in the early days. Meanwhile, demand for germanium in fiber optics communication networks, infrared night vision[?] systems, and polymerization catalysts increased dramatically. These end uses represented 85% of worldwide germanium consumption for 2000. Occurrence This metal is found in argyrodite[?] (sulfide[?] of germanium and silver); coal; germanite; zinc ores; and other minerals.

Germanium is obtained commercially from zinc ore processing smelter dust and from the combustion by-products of certain coals. A large reserve of this element is therefore in coal sources.

This metaloid can be extracted from other metals by fractional distillation of its volatile tetrachloride. This technique permits the production of ultra-high purity germanium.

In 1997 the cost of germanium was about US$ 3 per gram. The yearend price for germanium in 2000 was $1,150 per kilogram.

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