Germanium is a chemical element with an atomic number of 32 in the periodic table. There’s about 1.6 ppm of this substance in Earth’s crust. Being a member of the carbon family of elements, this metalloid has four valence electrons, low toxicity, and is transparent to infrared radiation.
Chemical and Physical Properties of Germanium
|Name Origin||Latin: Germania (Germany)|
|Atomic weight||72.61 g.mol-1|
|State at 20°C||Solid|
|Color||Grey / White|
|Electron configuration||[Ar] 3d104s24p2|
|Melting point||938.25°C, 1720.85°F, 1211.4 K|
|Boiling point||2833°C, 5131°F, 3106 K|
|Relative atomic mass||72.63|
|Key isotopes||73Ge, 74Ge|
|Crystal Structure||Cubic: Face centered|
|Orbitals||[Ar] 3d10 4s2 4p2|
|Covalent Radius||1.22 Å|
|Ionic Radius||.53 (+4) Å|
|Atomic Radius||1.52 Å|
|Atomic Volume||13.6 cm³/mol|
|Uses||Used in semiconductors, combined with tiny amounts of phosphorus, arsenic, gallium, and antimony.|
|Description||Steel-gray, brittle semi-metal.|
Germanium is a chemical element belonging to the carbon group of the periodic table. It can be found under the symbol Ge, with an atomic number 32, atomic mass of 72.59 g.mol-1, and electron configuration [Ar]3d104s24p2.
Sharing the same group with carbon and silicon, this element is classified as a metalloid, i.e. a substance displaying chemical properties of both metal and non-metal elements. Moreover, germanium shares both the electrical and semiconducting properties of silicone which is found to be a great substitute for the ‘element 32’.
It reaches its boiling point at 2830 °C, while the melting point is achieved at 937°C. Characterized by a diamond-like crystalline structure, germanium also has an electronegativity of 1.8 according to Pauling, whereas its atomic radius according to van der Waals measures 0.137 nm.
How Was Germanium Discovered?
In 1869, the father of the Periodic table – the great Russian chemist Dmitri Mendeleev – theorized the existence of a chemical element that was predicted to be the element 32 in his system of chemical elements.
Mendeleev’s Prediction of Germanium
According to Mendeleev’s chemical calculations, element 32 was to have an atomic mass of 72.64g.mol-1, a density of 5.45 g/cm3, and a high melting point, while its boiling point was postulated to be achieved at a temperature below 100°C.
Furthermore, this element was speculated to have a gray color and a feebly basic oxide activity. And in 1886, one of his German colleagues proved him right – Mendeleev’s predictions on the element 32 were very close to the new chemical element discovered by Clemens Winkler.
The Discovery of an Unusual Ore
Namely, in 1885, a miner employed at a silver mine near Freiberg had dug out an ore that was not seen by anyone before. A mineralogist from the Mining Academy, Albin Julius Weisbach (1833 – 1901) took the piece of ore and upon short analysis, he confirmed that it was a new type of mineral. After the short inspection of the mineral, Weisbach passed the sample to Clemens Alexander Winkler (1838-1904) for further analysis.
Clemens Winkler’s Discovery
This German chemist managed to detect 75% silver and 18% sulfur in the new mineral ore, but 7% of its composition was unaccounted for. However, this did not discourage him. He continued with his scientific attempts and chemical experiments in an effort to provide evidence for the chemical structure of the remaining 7% of the mineral labeled as argyrodite, Ag8GeS6.
Finally, in 1886, Winkler succeeded in recognizing a new metal-like element in the unfamiliar substance. Upon determining its properties, he also realized that it was the pure germanium form – the exact element Mendeleev predicted to take place below silicon in the periodic table.
How Did Germanium Get Its Name?
At first, Mendeleev assigned the name ‘ekasilicon’ to this hypothetical element. When Clemens Winkler isolated the new element from the mineral argyrodite, he thought that it would be convenient to label his discovery after the greater recent discovery in the world of science – the planet Neptune. Hence, neptunium was the name he attached to this new substance that was yet to be analyzed.
Unfortunately, little did he know that this name was already assigned to a substance in the mineral tantalite, discovered by one of his fellow colleagues. So, Winkler decided to name the new element after his country, Germany. Despite the fact that the German name of Winkler’s homeland was Deutschland, he decided on the Latin word ‘Germania’, since the Latin nomenclature was widely accepted in the scientific world for the naming of elements, occurrences, or processes.
Where Can You Find Germanium?
Germanium is not often found in its free elemental form in nature, and it doesn’t form its own minerals. Compared to other elements, this metalloid is as equally present in Earth’s crust as beryllium, molybdenum, and cesium, but it’s more abundant than cadmium, antimony, arsenic, and mercury. In the Universe, germanium is formed by neutron absorption that occurs after the initial burning of hydrogen and helium burning and the absorption of alpha-particles.
This substance is naturally present in the form of an oxide (GeO2) or a sulfide (GeS2) and in solutions such as germanic acid. The scarce germanium ores can be traced as the minerals germanite and argyrodite, but can also occur in the zinc ores and some plants.
The quantities of germanium intended for commercial use are obtained by processing zinc smelter flue dust or they are isolated from the by-products of zinc ore processing and combustion of certain coals. In addition, the zone-refining technique is used in the production of crystalline germanium. This procedure is aimed at purification until the metalloid reaches a form suitable for use in semiconductor manufacturing.
Germanium in Everyday Life
Until World War II, this chemical element was pretty much useless. However, during the Second World War, germanium was applied as one of the key elements in the making of high-resolution radar receivers. This application of the metalloid led to the invention of the first germanium transistor. From that time on, i.e. after 1945, germanium finds its application in the following instances:
- As a semiconductor, this metalloid is mainly used in germanium transistors, rectifiers, diodes, and integrated circuits. For this purpose, small amounts of arsenic, indium, gallium, indium, antimony, or phosphorus are often added to germanium;
- Added to glass, germanium oxide helps increase its high index of refraction; this is a very important property of the glass used in wide-angle lenses, camera lenses, solar cells, fiber-optics, and infrared devices;
- High purity germanium is applied for detection of radioactive sources, such as in airport security scanners and infrared night vision systems;
- Since both germanium and germanium oxide are transparent to infrared radiation, they are used in the manufacturing of infrared spectroscopes. In this application, bismuth germanate is used as a re-emitter of the absorbed light energy;
- Manufacturers of fluorescent lamps also make use of germanium as an alloying agent, where this substance has a function of a polymerization catalyst;
- In the manufacturing of pharmaceuticals and nutritional supplements.
How Dangerous Is Germanium?
According to the National Library of Medicine, germanium is mildly toxic. This chemical element is not a trace element found in our body.
As a result of the use of germanium dioxide (GeO2), carboxyethyl germanium sesquioxide, germanium tetrachloride (GeCl4), and germanium-lactate-citrate in some medicines for the treatment of AIDS and some types of cancer, chronic toxicity may occur. Namely, the accumulation of this substance in the soft tissues of the body upon prolonged use or exposure to it could lead to renal failure, muscle weakness, anemia, peripheral neuropathy, or even fatalities.
Environmental Effects of Germanium
Since germanium is heavier than air, it remains close to the ground when released. In this way, it’s more likely to accumulate in plants and surface waters. The technological applications of this element produce germanium contaminated waste that also has a negative impact on the environment.
Isotopes of Germanium
There are five naturally occurring isotopes of germanium: 70Ge, 72Ge, 73Ge, 74Ge, and 76Ge. Among them, the germanium-76 isotope has a half-life of 1.78 × 1021 years and low radioactivity. Germanium-74 is the most common form of this element that occurs in nature. Its abundance amounts up to 36%.
Up to the present, twenty-seven radioactive isotopes of germanium have been isolated. Their atomic mass ranges from 58 to 89. The most stable radioisotope of germanium is 68Ga. BY electron capture, it decays into the medically useful positron-emitting isotope 68Ga.
|Nuclide||Z||N||Isotopic mass (Da)
[n 2][n 3]
[n 4][n 5]
[n 8][n 5]
|Natural abundance (mole fraction)|
|Excitation energy||Normal proportion||Range of variation|
|61Ge||32||29||60.96379(32)#||39(12) ms||β+, p (80%)||60Zn||(3/2−)#|
|65Ge||32||33||64.93944(11)||30.9(5) s||β+ (99.99%)||65Ga||(3/2)−|
|β+, p (.01%)||64Zn|
|68Ge[n 9]||32||36||67.928094(7)||270.95(16) d||EC||68Ga||0+|
|76Ge[n 10]||32||44||75.9214026(18)||1.926(94)×1021 y||β−β−||76Se||0+||0.0783(7)|
|84Ge||32||52||83.93747(32)#||0.947(11) s||β− (89.2%)||84As||0+|
|β−, n (10.8%)||83As|
|85Ge||32||53||84.94303(43)#||535(47) ms||β− (86%)||85As||5/2+#|
|β−, n (14%)||84As|
|86Ge||32||54||85.94649(54)#||>150 ns||β−, n||85As||0+|
List of Germanium Compounds
Germanium forms stable oxidation states of +2 and +4. It oxidizes at 600°–700° C (1,100°–1,300° F), and readily reacts with concentrated nitric or sulfuric acid, or with a mixture of nitric and hydrochloric acids. Sodium hydroxide or potassium hydroxide dissolve germanium.
When germanium dioxide and basic oxides are exposed to high temperatures, they form germanates, which are used as phosphors.
The most common compounds of germanium [Ge+, Ge+2, Ge+4] are included in the following list:
- Germanium(IV) Phosphate
- Germanium(IV) Hydride
- Germanium(IV) Nitrate
- Germanium(IV) Bromide
- Germanium(IV) Iodide
- Germanium(IV) Chloride
- Germanium(III) Hydride
- Germanium(IV) Oxide
- Germanium(II) Oxide
- Germanium(IV) Chromate
- Germanium(II) Chloride
- Germanium(II) Sulfide
- Germanium (IV) Nitride
- Germanium(II) Fluoride
- Germanium(II) Bromide
- Germanium(IV) Sulfide
- Germanium(IV) Hypochlorite
- Germanium(IV) Chlorate
- Germanium(IV) Fluoride
- Germanium Telluride
- Germanium(II) Iodide
- Germanium Dichromate
- Germanium(II) Selenide
- Germanium(IV) Selenide
- Germanium(IV) Tungstate
- Germanium Cyanide
- Germanium(II) Phosphide
- Germanium(II) Sulfate
- Germanium(IV) Arsenide
5 Interesting Facts and Explanations
- During World War II, germanium was used in small quantities for making “point-contact Schottky diodes” for radar pulse detection.
- Germanium, boron, silicon, arsenic, antimony, tellurium, and polonium are classified as metalloids, i.e. chemical elements that display chemical properties of both metals and nonmetals (insulators). All metalloids are known to have semiconducting properties.
- Silicon and germanium are the members of Group 14 of the periodic table with the greatest commercial significance.
- This chemical element has the same crystal structure as the carbon atoms in diamond.
- The production of germanium transistors marked an entirely new era of semiconductor (solid-state) electronics which increased the germanium demand on the market in the postwar period. Nowadays, germanium is often replaced by silicone.