Germanium is a chemical element which is placed in the 14th group and 4th period in the periodic table. Symbol of the germanium element is Ge. It is a metalloid with the atomic number 32. As germanium is a metalloid, it shows some properties of metals and nonmetals as well. Metalloids are intermediate between metals and nonmetals. They are placed after metals and before the nonmetals in the periodic table. Thus, metalloids show the transition from metals to nonmetals.
Metalloid germanium belongs to the carbon family and shows similarity with neighboring elements silicon and tin. Element Ge is present after Si and just above Sn in the 4th group of the periodic table. It is a lustrous and grayish – white element.
Germanium was discovered late in the history of discovery of chemical elements. Although Russian Chemist Dmitri Mendeleev predicted its existence in 1869 and named it as ekasilicon, it was discovered in 1886 by German Chemist Clemens Alexander Winkler. He discovered it in argyrodite. Argyrodite is a rare silver germanium sulfide mineral. Its formula is Ag8GeS6. Germanium resembles arsenic and antimony in appearance.
The word Germanium comes from the country name Germany. Its discoverer Clemens Alexander Winkler named it after his country Germany. Clemens Winkler first named it Neptune but the name Neptune was already proposed for another element so he named it germanium. It is not found in abundance in Earth’s crust like iron, aluminum etc. It is mined from various ores such as sphalerite etc. Sphalerite is an ore of zinc although germanium is found in ores of silver, copper and lead as well.
It has 5 natural isotopes which are 70Ge, 72Ge, 73Ge, 74Ge and 76Ge. It has 27 synthetic isotopes as well which are unstable and have access to nuclear energy.
Germanium is a p- block element of the periodic table. Atomic number of germanium is 32. Its electronic configuration is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p2 or it can be written as [Ar] 3d10 4s2 4p2. It has 2 electrons in K – shell, 8 electrons in L – shell, 18 electrons in M – shell and 4 electrons in its outermost shell N.
Germanium is not one of the abundant elements in the Earth’s crust. It is found in only a few ores such as argyrodite, briartite, germanite and renierite etc. It has also been found in stars and in the atmosphere of Jupiter.
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Physical and chemical properties of germanium are listed below –
It is found as solid at STP.
Atomic mass of germanium is 72.6.
Its melting point is 938.25 ℃.
Boiling point of germanium is 2833 ℃.
It shows face centered diamond cubic crystal structure.
Its density is 5.323 g cm-3.
It is a semiconductor. It means its electrical conductivity value is between that of conductor and insulator.
According to the Pauling scale, its electronegativity is 2.01.
Its 1st ionization energy is 762kJ/mol.
It has 5 natural isotopes which are 70Ge, 72Ge, 73Ge, 74Ge and 76Ge. These all are stable isotopes. It has 27 synthetic isotopes which have high nuclear energy and are unstable.
It has a greyish – white appearance.
It has an allotrope – germanium.
At 250 ℃, germanium reacts with oxygen and forms oxide GeO2.
It does not react with dilute acids and bases.
It reacts with conc. hot H2SO4 and HNO3 slowly, but it reacts very violently with molten base.
It reacts with chlorine and forms germanium chloride. Reaction is given below –
Ge + 2Cl2 🡪 GeCl4
It reacts with bromine and forms germanium bromide. Reaction is given below –
Ge + 2Br2 🡪 GeBr4
Germanium is used in various fields mainly due to its properties such as semiconductor of electricity and high index of refraction of its oxide etc. Few of its uses are listed below –
Germanium oxide is used in wide angle camera lenses, microscopy and optical fibers.
It is used in rewritable DVDs.
It is an important infrared optical material which is used in windows, thermal imaging cameras etc.
It is used in military appliances as well such as fire - fighting instruments, night vision instruments etc.
It is used in alloys.
It is used in fluorescent lamps.
Its optical fibers are used in communications and in infrared optics.
It is used as a catalyst in many polymerization processes.
It is majorly used in solar cells and solar panels.
It is used in metallurgy in refining of metals.
It has space applications. It is used in place of multijunction photovoltaic cells.
It is used in gallium arsenide solar cells.
It is used in LEDs in its solid state.
It can be used in gas chromatography columns in place of SiO2.
It is used in the treatment of lung cancer and leukemia.
The Germanium element is not an essential element for plants and animals. As it is present in very minute quantities in nature. So, it has very little impact on the environment as a biohazard. Some germanium supplements are being used for treatment of many diseases. However, there is no evidence available stating its benefits although some evidence suggests that these Ge supplements are harmful. The US FDA has concluded that inorganic germanium presents potential human health hazards when taken as a nutritional supplement.
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