Ar - Argon

Argon

Argon

Atomic Number:	18
Atomic Weight:	39.948
Element Type:	Noble Gas
Crystal Structure:	Cubic Face Centered
Melting Point:	-189.35°C = -308.83°F = 83.8 K
Boiling Point:	-185.85°C = -302.53°F = 87.3 K
Critical Temp:	-122.28°C = -188.104°F = 150.87 K
Atomic Radius:	0.88 Å (Å = Angstrom = 10^-10 m)
Covalent Radius:	0.98 Å
Electronegativity:

History

(Gr. argos, inactive) Its presence in air was suspected by Cavendish in 1785,discovered by Lord Rayleigh and Sir William Ramsay in 1894.

Sources

The gas is prepared by fractionation of liquid air because the atmosphere contains0.94% argon. The atmosphere of Mars contains 1.6% of 40Ar and 5 p.p.m. of 36Ar.

'I beseech you to take interest in these sacred domains so expressively called laboratories. Ask that there be more and that they be adorned for these are the temples of the future, wealth and well-being. It is here that humanity will grow, strengthen and improve. Here, humanity will learn to read progress and individual harmony in the works of nature, while humanity's own works are all too often those of barbarism, fanaticism and destruction.'

Louis Pasteur
(1822-1895)