Argon

The argon is a chemical element, of symbol Ar and of Atomic number 18.

It belongs to the group of “rare gas” called family of the " before; gas inertes" and also family of the " rare gases " ; with the Helium, the Neon, the Krypton, the Xenon, the Radon and probably the Ununoctium. In spite of the name of its family, argon is not a rare gas: it is, behind the Diazote, the Dioxygène the third component in importance of the terrestrial atmosphere (0,933% in volume) and, so is one of the most used rare gases.

Notable characteristics

It is an element chemically inert, without color, savor and odorless in its forms Liquide S and Gaz euses. Argon is 2,5 times more soluble in water that the Diazote which has same solubility roughly as the Dioxygène.

There is no true known chemical compound which contains argon. Only a fluorohydrate HArF was synthesized recently (University of Helsinki-2000) at very low temperature (10 K).

Applications

Argon is employed:

  • for lighting since it does not react with the filament of a Lamp incandescent traditional even to Température S raised, whenever the Diazote is not appropriate like semi-inert gas;
  • like inert Gas of protection for the Arc cutting and the Cutting;
  • like inert Gas in fine chemistry to carry out handling in the absence of Oxygen;
  • like inert Gas in the blade of air of the insulating glazings with low emissivity;
  • as inert Gas in the tanks of exctinction of fire (ally with 50% of Nitrogen)
  • like not-reactive cover in the manufacture of the Titanium and other reactive elements;
  • like protective atmosphere for the manufacture of crystals of Silicon and ultrapure Germanium for the Electronics industry.
  • in Plunged underwater to inflate the tight combination, because of its heat insulator not-reagent properties.
Argon-39 was employed in particular to date from subterranean water

History

The presence in the air of argon (coming from the Greek argos “lazy” meaning) was suspectée by Henry Cavendish as of 1785 but its discovery by Lord Rayleigh and Sir William Ramsay awaited 1894.

They were put on the track by the difference in density between nitrogen produces chemically and that extracted the air by elimination of oxygen. The split distillation of the Liquid air enabled them to produce a notable quantity in of it 1898 and consequently occasion to insulate the Néon and the Xénon.

The first molecule implying argon (HArF) was synthesized in 2000.

Occurrence

Argon is isolated from the liquid air by fractionation since the atmosphere contains only 0,94% of this gas. On the other hand, the atmosphere of Mars contains argon-40 1,6% and 5 ppm of argon-36.

Isotopes

The principal isotopes of argon found on ground are argon-40, -36, and -38. The natural Potassium, 40K, has a Demi-vie 1,250×109ans, and disintegrates by Capture of electron and emission of Positron out of argon-40 (11,2%) stable, or in Calcium -40 (88,8%) also stable by Disintegration β -. These properties and as well as the relationship between the formed by-products are employed to determine the age of the rocks.

In the Terrestrial atmosphere, argon-39, as well as argon-40, are produced by the activity of the cosmic rays. Under the surface of the Ground, it is also produced by Capture of neutron S of potassium-39 or by emission of particles alpha of the Calcium. Argon-37 is produced by the disintegration of calcium-40, the result of nuclear explosions underground, it has a Demi-vie 35 days.

See too

Simple: Argon

Random links:Tourtouse | USS Tejas (1892) | Commenailles | Cino da Pistoia | Kevin Durand | Frederic-François Ier de Mecklembourg-Schwerin | Hewlett-Packard