Germanium Element Facts


Germanium. Image Ref. (1)


Data Zone

Classification: Germanium is a metalloid
Color: gray-white
Atomic weight: 72.64
State: solid
Melting point: 938 oC, 1210.6 K
Boiling point: 2830 oC, 3103 K
Electrons: 32
Protons: 32
Neutrons in most abundant isotope: 42
Electron shells: 2,8,18,4
Electron configuration: [Ar] 3d10 4s2 4p2
Density @ 20oC: 5.323 g/cm3
Show more, including: Heats, Energies, Oxidation, Reactions, Compounds, Radii, Conductivities
Atomic volume: 13.6 cm3/mol
Structure: diamond structure
Hardness: 6 mohs
Specific heat capacity 0.32 J g-1 K-1
Heat of fusion 36.940 kJ mol-1
Heat of atomization 377 kJ mol-1
Heat of vaporization 334.3 kJ mol-1
1st ionization energy 762.1 kJ mol-1
2nd ionization energy 1537.4 kJ mol-1
3rd ionization energy 3301.7 kJ mol-1
Electron affinity 120 kJ mol-1
Minimum oxidation number -4
Min. common oxidation no. -4
Maximum oxidation number 4
Max. common oxidation no. 4
Electronegativity (Pauling Scale) 2.01
Polarizability volume 6.1 Å3
Reaction with air mild, w/ht ⇒ GeO2
Reaction with 15 M HNO3 mild, ⇒ Geiv, NOx
Reaction with 6 M HCl none
Reaction with 6 M NaOH none
Oxide(s) GeO, GeO2
Hydride(s) GeH4, Ge2H6 + more
Chloride(s) GeCl2, GeCl4
Atomic radius 122.3 pm
Ionic radius (1+ ion)
Ionic radius (2+ ion) 87 pm
Ionic radius (3+ ion)
Ionic radius (1- ion)
Ionic radius (2- ion)
Ionic radius (3- ion)
Thermal conductivity 60.2 W m-1 K-1
Electrical conductivity 3 S m-1
Freezing/Melting point: 938 oC, 1210.6 K

Discovery of Germanium

Dr. Doug Stewart

Germanium was one of the elements whose existence was predicted in 1869 by Russian chemist Dmitri Mendeleev, after he noticed a gap between silicon and tin in his periodic table. Mendeleev provisionally called the predicted element eka-silicon.

Germanium was discovered by Clemens A. Winkler in 1886, in Germany, in a mineral sample from a silver mine.

Analysis indicated the sample – a rather rare mineral called argyrodite – contained 73 – 75% silver, 17 – 18% sulfur, 0.2% mercury, and 6 – 7% a new element, which Winkler named germanium.

Mendeleev had predicted the new element’s density would be 5.5 g/cm3 and its atomic weight would be 70.
His predictions proved to be rather good.

Winkler’s name for the element comes from the Latin ‘Germania’ meaning Germany.

Germanium can harness solar energy much more efficiently than silicon.

Appearance and Characteristics

Harmful effects:

Germanium is not known to be toxic.


Germanium is a lustrous, hard, gray-white semi-metallic element with a crystalline and brittle structure.

It is a semiconductor.

Germanium and the oxide are transparent to infrared radiation.

Germanium also has the unusual property that (like water) it expands as it freezes.

Four other elements expand when they freeze; silicon, bismuth, antimony and gallium.

Uses of Germanium

The most common use of germanium is as a semiconductor.

Germanium is used in transistors and in integrated circuits.

It is used as an alloying agent and as a catalyst.

It is also used in infrared spectroscopes and infrared detectors.

Some germanium compounds are useful because they are toxic to bacteria but are harmless for mammals.

Abundance and Isotopes

Abundance earth’s crust: 1.5 parts per million by weight, 0.42 parts per million by moles

Abundance solar system: 200 parts per billion by weight, 3 parts per billion by moles

Cost, pure: $360 per100g

Cost, bulk: $120 per 100g

Source: The main ore of germanium is germanite, which is about 7% germanium. Commercially, germanium is obtained as a byproduct of metal refining and from some coal ashes.

Isotopes: Germanium has 24 isotopes whose half-lives are known, with mass numbers 58 to 85. Naturally occurring germanium is a mixture of five isotopes and they are found in the percentages shown: 70Ge (21.2%), 72Ge (27.7%), 73Ge (7.7%), 74Ge (35.9%) and 76Ge (7.4%). The most abundant is 74Ge at 35.9%.


1. Photo: Gibe, GNU Free Documentation License.

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