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About Germanium

Germanium Bohr

When Mendeleev published his first Periodic Table of the Elements in 1869, he included several as-yet undiscovered elements. He gave each a temporary name and predicted its properties based on the surrounding elements. One of these was named ekasilicon, and Mendeleev almost perfectly predicted the properties of the actual element, which was discovered by Clemens Winkler in 1886 and named after his native Germany: thus, germanium.

Germanium is a semiconducting metalloid with properties similar to silicon, and its use in electronic devices actually pre-dated the use of the more famous element. The first transistors were produced from germanium in Bell labs in 1947. Ultimately, the technologies available for use with silicon and the abundance of silicon led to many more semiconductor applications using silicon, including standard computer chips, and for many years germanium played a limited role in semiconductor devices. However, today new technologies are again making germanium a key material for electronics applications. Germanium is preferable to silicon in some types of photovoltaic cells used to harvest solar energy, and is used as a key substrate material in production of high-brightness LEDs for flashlights, automobile tail lights, cameras, traffic signals, and display screens. As an LED component, germanium is sometimes preferable to the alternative, gallium arsenide, as it breaks less frequently and poses fewer disposal issues. Additionally, microchip designs using germanium-on-insulator or silicon-germanium technology are seeing increased use.

Another key use of germanium comes from the favorable optical properties of it and some of its compounds. Germanium oxide has a high index of refraction and low optical dispersion, making it appropriate for use in wide-angle lenses and some microscopes. Germanium oxide also imparts some of these properties when used as a dopant in silica glass, and is used as such in the core of optical fibers. An additional useful optical property is that germanium glass is transparent to infrared radiation. It is therefore used in thermal imaging cameras, night vision systems, and sensitive infrared detectors. Another use of germanium in optical systems is in the material germanium-antimony-tellurium, or GeSbTe, a phase change material used in rewritable optical disks (CD-RW, DVD-RW) and other phase change memory devices.

In addition to its electronic and optical applications, germanium also finds uses in a few other key areas. Germanium oxide is used as a catalyst in the making of many plastics. When germanium is added in small amounts to sterling silver, it reduces firescale and tarnish, and makes the final metal harder. Contrary to past beliefs, germanium has not been shown to have any medical function and is considered potentially hazardous if consumed; nonetheless some nutritional supplements contain the element.

Though germanium is not particularly rare, it is not contained in any mineral in large enough percentages to be worth mining for germanium specifically. Instead, germanium is derived from concentrates produced as byproducts of mining for other metals, particularly zinc, and is additionally recovered from the fly ash of some coal power plants.

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Germanium is a very important semiconductor and is also finding many other applications including use as an alloying agent, as a phosphor in High Purity (99.999%) Germanium Oxide (GeO2) Powderfluorescent lamps, and as a catalyst. Germanium and germanium oxide are transparent to the infrared and are used in infrared spectroscopes High Purity (99.99%) Germanium (Ge) Sputtering Targetand other optical equipment, including extremely sensitive infrared detectors. The high refractive index and dispersion properties of its oxides have made germanium useful as a component of wide-angle camera lenses and microscope objectives. Elemental or metallic forms of Germanium include pellets, rod, wire and granules for evaporation source material purposes. Germanium oxide is available in forms including powders and dense pellets for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Germanium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Germanium Properties

Germanium (Ge) atomic and molecular weight, atomic number and elemental symbolGermanium is a Block P, Group 14, Period 4 element. The number of electrons in each of germanium's shells is 2, 8, 18, 4 and its electron configuration is [Ar] 3d10 4s2 4p2. Germanium Bohr ModelThe germanium atom has a radius of and its Van der Waals radius is In its elemental form, CAS 7440-56, germanium is a brittle grayish white semi-metallic element. Germanium is too reactive to be found naturally on Earth in its native state. It is commercially obtained from zinc High Purity (99.999%) Germanium (Ge) Metal ores and certain coals. It is also found in argyrodite and germanite. Germanium was first discovered by Clemens Winkler in 1886. The name Germanium originates from the Latin word "Germania" meaning "Germany".

Symbol: Ge
Atomic Number: 32
Atomic Weight: 72.63
Element Category: metalloid
Group, Period, Block: 14, 4, p
Color: grayish white
Other Names: N/A
Melting Point: 938.25 °C, 1720.85 °F, 1211.40 K
Boiling Point: 2833 °C, 5131 °F, 3106 K
Density: 5.323 g·cm3
Liquid Density @ Melting Point: 5.60 g·cm3
Density @ 20°C: 5.323 g/cm3
Density of Solid: 5323 kg·m3
Specific Heat: N/A
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 34.7
Heat of Vaporization (kJ·mol-1): 327.6
Heat of Atomization (kJ·mol-1): 373.8
Thermal Conductivity: 60.2 W·m-1·K-1
Thermal Expansion: 6.0 µm/(m·K)
Electrical Resistivity: (20 °C) 1 µ·m
Tensile Strength: N/A
Molar Heat Capacity: 23.222 J·mol-1·K-1
Young's Modulus: 103 GPa
Shear Modulus: 41 GPa
Bulk Modulus: 75 GPa
Poisson Ratio: 0.26
Mohs Hardness: 6
Vickers Hardness: N/A
Brinell Hardness: N/A
Speed of Sound: (20 °C) 5400 m·s-1
Pauling Electronegativity: 2.01
Sanderson Electronegativity: 2.62
Allred Rochow Electronegativity: 2.02
Mulliken-Jaffe Electronegativity: 2.33 (sp3 orbital)
Allen Electronegativity: 1.994
Pauling Electropositivity: 1.99
Reflectivity (%): 54
Refractive Index: N/A
Electrons: 32
Protons: 32
Neutrons: 41
Electron Configuration: [Ar] 3d10 4s2 4p2
Atomic Radius: 122 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 122 pm
Covalent Radius (Å): 1.2
Van der Waals Radius: 211 pm
Oxidation States: 4, 3, 2, 1, 0, -1, -2, -3, -4
Phase: Solid
Crystal Structure: diamond cubic
Magnetic Ordering: Diamagnetic[
Electron Affinity (kJ·mol-1) 118.966
1st Ionization Energy: 762.18 kJ·mol-1
2nd Ionization Energy: 1537.47 kJ·mol-1
3rd Ionization Energy: 3302.15 kJ·mol-1
CAS Number: 7440-56-4
EC Number: 231-164-3
MDL Number: MFCD00085310
Beilstein Number: N/A
SMILES Identifier: [Ge]
InChI Identifier: InChI=1S/Ge
PubChem CID: 6326954
ChemSpider ID: 4885606
Earth - Total: 7.6 ppm 
Mercury - Total: 1.24 ppm
Venus - Total: 8.4 ppm
Earth - Seawater (Oceans), ppb by weight: 0.06
Earth - Seawater (Oceans), ppb by atoms: 0.0051
Earth -  Crust (Crustal Rocks), ppb by weight: 1400
Earth -  Crust (Crustal Rocks), ppb by atoms: 390
Sun - Total, ppb by weight: 200
Sun - Total, ppb by atoms: 3
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: 21000
Meterorite (Carbonaceous), ppb by atoms: 4900
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 200
Universe, ppb by atom: 3
Discovered By: Clemens Winkler
Discovery Date: 1886
First Isolation: N/A

Health, Safety & Transportation Information for Germanium

Germanium is not toxic in its elemental form; however, safety data for Germanium metal, nanoparticles and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific Germanium material or compound referenced in the Products tab.

Safety Data
Material Safety Data Sheet MSDS
Signal Word Warning
Hazard Statements H315-H319-H335
Hazard Codes Xi
Risk Codes 36/37/38
Safety Precautions 26-36/39
RTECS Number LY5200000
Transport Information N/A
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Exclamation Mark-Acute Toxicity

Germanium Isotopes

Germanium (Ge) has five naturally occurring isotopes, 70Ge, 72Ge, 73Ge, 74Ge, and 76Ge.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
58Ge 57.99101(34)# Unknown 2p to 56Zn 0+ N/A 441.04 -
59Ge 58.98175(30)# Unknown 2p to 57Zn 7/2-# N/A 458.44 -
60Ge 59.97019(25)# 30# ms ß+ to 60Ga; 2p to 58Zn 0+ N/A 476.77 -
61Ge 60.96379(32)# 39(12) ms ß+ + p to 60Zn; ß+ to 61Ga (3/2-)# N/A 491.37 -
62Ge 61.95465(15)# 129(35) ms ß+ to 62Ga 0+ N/A 507.83 -
63Ge 62.94964(21)# 142(8) ms ß+ to 63Ga (3/2-)# N/A 520.57 -
64Ge 63.94165(3) 63.7(25) s EC to 64Ga 0+ N/A 536.1 -
65Ge 64.93944(11) 30.9(5) s EC to 65Ga (3/2)- N/A 546.04 -
66Ge 65.93384(3) 2.26(5) h EC to 66Ga 0+ N/A 559.71 -
67Ge 66.932734(5) 18.9(3) min EC to 67Ga 1/2- N/A 568.72 -
68Ge 67.928094(7) 270.95(16) d EC to 68Ga 0+ N/A 580.52 -
69Ge 68.9279645(14) 39.05(10) h EC to 69Ga 5/2- 0.735 589.53 -
70Ge 69.9242474(11) STABLE - 0+ N/A 600.41 20.84
71Ge 70.9249510(11) 11.43(3) d EC to 71Ga 1/2- 0.547 608.49 -
72Ge 71.9220758(18) STABLE - 0+ N/A 618.43 27.54
73Ge 72.9234589(18) STABLE - 9/2+ -0.8794669 625.58 7.73
74Ge 73.9211778(18) STABLE - 0+ N/A 635.52 36.28
75Ge 74.9228589(18) 82.78(4) min ß- to 75As 1/2- 0.51 642.66 -
76Ge 75.9214026(18) 1.78(8)E+21 y - to 76Se 0+ N/A 651.67 7.61
77Ge 76.9235486(18) 11.30(1) h ß- to 77As 7/2+ N/A 657.89 -
78Ge 77.922853(4) 88(1) min ß- to 78As 0+ N/A 666.9 -
79Ge 78.9254(1) 18.98(3) s ß- to 79As (1/2)- N/A 672.18 -
80Ge 79.92537(3) 29.5(4) s ß- to 80As 0+ N/A 680.26 -
81Ge 80.92882(13) 7.6(6) s ß- to 81As 9/2+# N/A 685.55 -
82Ge 81.92955(26) 4.55(5) s ß- to 82As 0+ N/A 692.69 -
83Ge 82.93462(21)# 1.85(6) s ß- to 83As (5/2+)# N/A 696.11 -
84Ge 83.93747(32)# 0.947(11) s ß- to 84As; ß- + n to 83As 0+ N/A 701.4 -
85Ge 84.94303(43)# 535(47) ms ß- to 85As; ß- + n to 84As 5/2+# N/A 703.89 -
86Ge 85.94649(54)# >150 ns ß- + n to 85As; ß- to 86As 0+ N/A 709.17 -
87Ge 86.95251(54)# 0.14# s Unknown 5/2+# N/A 711.66 -
88Ge 87.95691(75)# >=300 ns Unknown 0+ N/A 716.01 -
89Ge 88.96383(97)# >150 ns Unknown 3/2+# N/A 717.57 -