Chemistry - Helium

Introduction

• 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 −

  • Helium-3 and

  • Helium-4

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.