Facts About Argon

Credit: Greg Robson/Creative Commons, Andrei Marincas | Shutterstock
Atomic Number: 18
Atomic Symbol: Ar
Atomic Weight: 39.948
Melting Point: -308.7 F (-189.35 C)
Boiling Point: -302.4 F (-185.85 C)

Word origin: The word argon comes from the Greek word argos (inactive).

Discovery: Henry Cavendish suspected that argon was present in the air in 1785 but it was not realized as a distinct substance until 1894 when Lord Rayleigh and Sir William Ramsay discovered it.

Properties of argon

Argon is colorless and odorless in both its gas and liquid forms. It is a very inert gas and it does not form true chemical compounds. [See Periodic Table of the Elements]

Argon is two-and-one-half times as soluble in water as nitrogen, making it about as soluble as oxygen.

Natural argon is a mixture of three isotopes. Scientists are aware of 12 other radioactive isotopes.

Arc welding
Argon gas is used in arc welding.
Credit: chinahbzyg | Shutterstock

Sources of argon

Argon gas is prepared by fractionation of liquid air. This is possible because Earth's atmosphere is 0.94 percent argon.

Uses of argon

Argon helps light our world. It is used in electric light bulbs and in fluorescent tubes at a pressure of about 400 Pa. It is also used in filling photo tubes, glow tubes, and more.

Argon is used as an inert gas shield for arc welding and cutting, as a blanket during production of titanium and other reactive elements, and as a protective atmosphere for growing silicon and germanium crystals.

(Source: Los Alamos National Laboratory)

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