- Chemistry Notes for UPSC IAS Prelims (Part II)
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- Chemistry - Helium
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Chemistry - Helium
Helium is the second lightest (after hydrogen) and second most abundant element in the universe.
The symbol of Helium is ‘He’ and atomic number is ‘2.’
In the periodic table, Helium is the first in the noble gas group.
Helium is named after the name of the Greek god of the Sun, ‘Helios.’
Salient Features of Helium
Helium is a colorless, odorless, tasteless, inert, non-toxic, and monatomic gas.
The boiling point (-268.90C) of helium is the lowest among all the elements.
Helium is typically composed of two electrons in atomic orbitals and surrounded by a nucleus, which consists two protons and two neutrons.
Occurrence of Helium
Most helium found in the universe belong to helium-4, and it is believed to have been formed during the Big Bang.
Major share of new helium is typically being created by nuclear fusion of hydrogen in stars including the Sun.
Though there is continuous creation of new helium; nevertheless, the availability of helium on the earth is substantially low because being the light weight element, it easily escapes into space.
In heterosphere (outer atmosphere) of the earth, helium is one of the most abundantly found elements (gases).
In the earth’s crust, helium is characteristically found in large amounts in the minerals of uranium and thorium.
Compounds of Helium
Following are the major compounds of helium −
Disodium helide - Na2He
Cristobalite He II (Silicates) - SiO2He
Dihelium arsenolite - As4O6•2He
Isotopes of Helium
There are about nine known isotopes of helium, but following two are the most stable isotopes −
Uses of Helium
Because of having low density, low boiling point, low solubility, high thermal conductivity, helium is widely used element; the most popular example is – use of helium in balloon.
Major chunk of helium has cryogenic applications, such as, cooling the superconducting magnets used in medical MRI scanners and NMR spectrometers.
Helium is also used as a protective gas in growing silicon and germanium crystals.
Helium is also used in and gas chromatography and in titanium and zirconium production.
Helium is used in supersonic wind tunnels.
Helium is also applied as a shielding gas in an arc welding processes.