Occurrence, Properties, Uses and Isotopes of Argon


Argon is a noble gas in group 18 of the periodic table. Its atomic number is 18 whereas its atomic mass is 39.94. Argon has 18 electrons. It has 18 protons and 22 neutrons in its nucleus. Argon is represented by the symbol “Ar”. It was the first noble gas that was discovered.

Naming and History

The name of Argon is from the Greek word “Argos” for idle or inactive.

  • Sir Henry Cavendish

The first indication of its existence originated from English scientist Sir Henry Cavendish back in 1785. He noted that about 1% of air would not react also under extreme conditions. That 1% was argon.

  • Lord Rayleigh

In 1892 English physicist Lord Rayleigh revealed that no matter exactly how it was prepared, oxygen was constantly 15.882 times denser than hydrogen.

  • William Ramsay

Rayleigh’s paper stirred up the significant rate of interest of Scottish chemist William Ramsay, that had currently known the problem. Rayleigh and also Ramsay accomplished better experiments, interacting with one another regarding their progression.

In August 1894 Ramsay took air and also removed its elements– oxygen, carbon dioxide, and nitrogen. He eliminated the nitrogen by reacting it with magnesium. After getting rid of all the recognized gases from the air, he discovered gas staying that occupied one-eightieth of the original volume. Its spectrum matched no known gas.

  • Rayleigh and also Ramsay created a joint paper in 1895 notifying the world of their discovery.
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Argon is the most abundant noble gas on Earth. It is the third most abundant element in the air. It constitutes about 1%. In the earth’s atmosphere, cosmic ray activity produces radioactive Ar-39.  Some traces of argon are present in Earth’s crust.

Potassium minerals contain small amounts of argon due to radioactive decay. Argon can be obtained as a byproduct of liquid air after removing oxygen and nitrogen.

Properties of Argon

Argon is colorless and odorless both in gaseous as well as liquid forms. When it is excited in high electric voltage, it produces a violet glow. The melting point of argon is -189.35°C and its boiling point is -185.85°C.

Argon exists as a gas at room temperature and it has a density of 0.0017837 grams per cubic centimeter. It is inert gas but photolysis of hydrogen fluoride with solid argon can produce argon Fluro hydride.

Argon in Biological System

There is no significant role known in biological systems. It is considered to be non-toxic.

Uses of Argon


  • Due to its inertness, it is used in lighting bulbs where it does not react with filament.
  • It is widely used in the metal industry for arc welding and cutting.
  • Argon is used in fluorescent lights and low-energy bulbs. Low energy bulbs contain mercury and argon. When electric current pass it glows.
  • Medical lasers for the treatment of blood vessel leakage in eyes, retinal detachment, macular degeneration, etc. uses argon.
  • Argon is used to fill space between double glazed window panes.
  • Argon is used for silicon and germanium crystal growth to provide them an inert atmosphere.
  • Argon is most exotically used in the tyers of luxury cars.
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Isotopes of Argon

Almost 22 isotopes of argon are known from masses Ar-31 to Ar-51 and Ar-53. The radioactive isotopes of Ar-39 and Ar-40 are used in radioactive dating. These are used in determining the ages of rocks, ice ages, igneous rocks, groundwater, etc.