Argon

Images

Image

Attribution: Alchemist-hp

Animated Argon

History

From the Greek argos, inactive. Its presence in air was suspected by Cavendish in 1785, discovered by Lord Raleigh and Sir William Ramsay in 1894.

Sources

The gas is prepared by fractionation of liquid air because the atmosphere contains 0.94% argon. The atmosphere of Mars contains 1.6% of 40Ar and 5 ppm of 36Ar.

Uses

It is used in electric light bulbs and in fluorescent tubes at a pressure of about 400 Pa. and in filling photo tubes, glow tubes, etc. Argon is also used as an inert gas shield for arc welding and cutting, as blanket for the production of titanium and other reactive elements, and as a protective atmosphere for growing silicon and germanium crystals.

Isotopes

Naturally occurring argon is a mixture of three isotopes. Twelve other radioactive isotopes are known to exist.

General Info

AtomicNumber
18
Symbol
Ar
Name
Argon

Atomic Info

Appearance
AtomicWeight
39.948(1)
Color
80D1E3
ElectronicConfiguration
[Ne] 3s2 3p6
ElectronegativityInPauling
AtomicRadiusInPM
97
IonRadiusInPM
VanDerWaalsRadiusInPM
188
IEinKJmol
1521
EAinKJmol
0
OxidationStates
StandardState
gas
BondingType
atomic
MeltingPoint
84
BoilingPoint
87
Density
0
State
Noble gas
DiscoveredYear
1894