Name Argon
Symbol Ar
Atomic Number 18
Atomic Mass 39.948 atomic mass units
Number of Protons 18
Number of Neutrons 22
Number of Electrons 18
Melting Point -189.3 C
Boiling Point -186.0 C
Density 1.784 grams per cubic centimeter
Normal Phase Gas
Family Noble Gases
Period 3
Cost 50 cents per 100 grams



Origin of Name From the Greek word "argos," which means inactive
Date and Place of Discovery 1894 in Scotland
Discovered by Sir William Ramsay and Lord Rayleigh (aka John William Strutt)
Common Compounds There are no common compounds because its oxidation number is zero which means it does not form compounds easily.
Interesting facts
  • Argon is created when the potassium in the earth's crust decays.
  • It's the most abundant of rare gases.
  • It emits light when electronically excited.
  • About .94% of the earth's atmosphere contains argon.
  • About 1.6% of Mars' atmosphere contains argon.
Common Uses
  • Light bulbs
  • Lasers
  • Glow tubes
  • Welding
  • Plasma globes
  • Dating of ground water


Photo Courtesy of
Chemical Elements
Jefferson Lab
Web Elements

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