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Germanium

What is Germanium

Germanium (pronunciation: jer-MAY-ni-em) is a shiny, silvery element classified as a metalloid and represented by the chemical symbol Ge [1, 2]. As a relatively inactive element, germanium does not react with oxygen at 20°C and is insoluble in water but its compound, germanium dioxide, is slightly soluble in water [3].

Germanium Symbol

Isotopes

Its five stable isotopes, germanium-70, germanium-72, germanium-73, germanium-74, and germanium-76, occur naturally out of which germanium-74 is the most common with a natural abundance of around 36% [4]. Germanium-76 is slightly radioactive with a half-life period of 1.6 X 1021 years and a natural abundance of around 7% [1, 4]. It also has more than 27 artificially produced radioisotopes whose atomic mass ranges from 58-89 [4].

Where is Germanium Found

Germanium rarely occurs as pure ore compounds and is found in small amounts in minerals like argyrodite and germanite [1]. While it can also be obtained from zinc ores, flue dust from zinc smelting is a commercial source of germanium [1]. Moreover, it can be recovered from coal combustion by-products [1].

The top 3 germanium producing countries include China, Russia, and Germany [1].

Germanium

History

Origin of its Name: It is named after ‘Germania’, the Latin word for Germany [1].

Who discovered it: The German chemist Clemens A. Winkler is known to be the discoverer of germanium [1].

When and How was it Discovered

In September 1885, an unusual mineral ore was found by a miner who was working in the Himmelsfürst mine in the Freiberg district of Germany [1]. He passed it to Albin Weisbach, the German mineralogist who confirmed it was a new mineral, which we now know as Argyrodite (Ag8GeS6) [1].  His colleague Clemens Winkler analyzed the new mineral and found that it consisted of 18% sulfur, 75% silver, while the remaining 7% could not be explained [1, 5]. By February 1886, Winkler realized that it was a new element and named it germanium, the properties of which were earlier predicted by the Russian chemist Dmitri Mendeleev [1, 5].

Germanium Transistor

Germanium Identification
Atomic number 32 [1]
CAS number 7440-56-4 [1]
Position in the periodic table Group Period Block
  14 [1] 4 [1] p [1]

Location of Germanium in the Periodic Table

Properties and Characteristics of Germanium

General Properties
Relative atomic mass 72.630 [1]
Atomic mass 72.630 amu [1]
Molar mass 72.6400 g/mol [6]
Allotropes α-Ge, β-Ge [1]

Physical Properties
Color Silvery-white [1, 6]
Melting point/freezing point 938.25 °C, 1720.85 °F [1]
Boiling point 2833 °C, 5131 °F [1]
Density 5.3234 g cm-3 [1]
State of matter at room temperature (solid/liquid/gas) Solid [1, 5]
Hardness
– Brinell 7273.4 MPa [7]
– Mohs 6 [7]
– Vickers 8012.03 MPa [7]
Electrical conductivity 2000 S/m [7]
Charge +4, +2 [8]
Thermal (heat) conductivity 60 W/(m K) [7]
Specific heat 320 J kg-1 K-1 [1]
Bulk modulus Unknown [1]
Shear modulus Unknown [1]
Young’s modulus Unknown [1]
Vapor pressure
– Temperature (K) 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
– Pressure (Pa) – – – – – – – – – – –

Chemical Properties
Oxidation state/Oxidation number −4, (−3), (−2), (−1), +1, +2, +3, +4 [1]
Isotopes Isotope Mass Abundance (%) Half-life Mode of decay
  70Ge 69.924 20.57 – –
  72Ge 71.922 27.45 – –
  73Ge 72.923 7.75 > 1.8 X 1023 y β-
  74Ge 73.921 36.5 – –
  76Ge 75.921 7.73 1.6 X 1021 y β-β-

Germanium Lewis Dot Structure with Periodic Table

Atomic Data of Germanium (Element 32)

Valence electrons 4 [9]
Quantum numbers
– n 4 [10]
– ℓ 1 [10]
– mℓ 0 [10]
– ms +1/2 [10]
Electron configuration (noble gas configuration) [Ar] 3d104s24p2 [1]
Atomic structure
– Number of electrons 32 [5]
– Number of neutrons 42 [5]
– Number of protons 32 [5]
Radius of Atom
– Atomic radius 2.11 Å [1]
– Covalent radius 1.20 Å [1]
Electronegativity (Pauling-scale) 2.01 [1]
Electron affinity 118.939 kJ mol-1 [1]
Ionization energy (kJ mol-1) 1st 2nd 3rd 4th 5th 6th 7th 8th
  762.179 1537.456 3302.124 4410.644 9021.4 – – –

Germanium Electron Configuration (Bohr Model)

What is it Used for

  • Pure germanium was usually doped with gallium, arsenic, or other elements for use as a semiconductor in transistors and integrated circuits of electronic applications [1, 5]. Today, it has been replaced by other semiconductors [1].
  • Because of its high dispersion and refraction index, germanium is commonly used in objective lenses for microscopes and wide-angle lenses for camera [1].
  • It is added to alloys, including silver, for stopping it from tarnishing [1]. It can as well be used as a catalyst and in fluorescent lamps [1, 5].
  • Since germanium and its oxide are transparent in infrared wavelength, they make excellent infrared optical material and are utilized in infrared spectroscopes [1].
  • Organic germanium, sold as supplements, is believed to be useful for promoting a healthy immune system, destroying free radicals, and supplying oxygen in the body [11]. It is claimed to be a remedy for health conditions like allergies, arthritis, HIV, cancer, and asthma [11].
  • It is used in making solar cells that are placed in solar panels [6].

Germanium Diode

Is Germanium Toxic

The element 32 is considered non-toxic [1]. Although some of its compounds are slightly toxic in mammals, they are known for their anti-bacterial properties for which researchers are now looking into their probable use in medications [1].

Interesting Facts

  • Germanium’s graphical representation features an image of a transistor, which indicates the early use of the element [1].
  • Being a metalloid, germanium has the properties of both nonmetals and metals [6].
  • Like water, germanium is known to expand on freezing [6].
  • It was commonly used in high-resolution radar during the Second World War [6].

Germanium Crystal

Germanium Cost

The cost of pure germanium is around $3.60 per gram, and in bulk, its price is around $1.20 per gram [5].

    References

  1. http://www.rsc.org/periodic-table/element/32/germanium
  2. https://education.jlab.org/itselemental/ele032.html
  3. https://pubchem.ncbi.nlm.nih.gov/compound/Germania#section=Top
  4. https://education.jlab.org/itselemental/iso032.html
  5. https://www.chemicool.com/elements/germanium.html
  6. https://www.livescience.com/29520-germanium.html
  7. http://periodictable.com/Elements/032/data.html
  8. Lenntech.com
  9. http://hyperphysics.phy-astr.gsu.edu/hbase/Solids/sili.html
  10. http://chemistry-reference.com/q_elements.asp?Symbol=Ge&language=en
  11. https://www.healthline.com/health/is-germanium-a-miracle-cure

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