argon

Name argon
Symbol Ar
Atomic Weight 39.948
Atomic Number 18
CAS ID 7440-37-1
Group Number 18
Group Name Noble Gas
Period Number 3
Origin of Name Greek, argos = "inactive."
Year Discovered 1894
Discovery Credits Discovered by Lord Rayleigh (London) and Sir William Ramsay (Bristol), UK
Class Non-metallic
Color Silvery White
Standard State Gas at 77 F & 298 K
Description Colorless, odorless gas comprising 1 percent of the atmosphere. Used as inert atmosphere in lamps and high temperature metallurgy. Found in potassium-bearing minerals as a trapped gas due to the radioactive decay of K40

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