Discovered | Name | Characteristics | Uses

Argon is a nonmetal in the 3rd period of Group VIIIA, the rare gas elements. Other members of the group are helium (He), neon (Ne), krypton (Kr), xenon (Xe), and radon (Rn).

Argon's presence in air was suspected by Cavendish in 1785 but the element was first separated from air by Lord Rayleigh and Ramsay in 1894.

Lord Rayleigh and Ramsay found argon initially by noticing that "nitrogen" isolated from air had a slightly higher density than pure nitrogen generated from an azide compound. Subsequently they prepared it by fractional distillation of liquid air, the atmosphere containing 0.94% argon; this is the method now used commercially.

The name is derived from the Greek word a-ergon, which means no work or no action, indicating the inactive nature of the element; the symbol Ar is derived from the name.

Argon is colorless, tasteless, and odorless, both as a gas and liquid. It is by far the most abundant rare gas on the earth's surface. In the solid state the element has a face-centered cubic structure.

Argon is twice as soluble in water as nitrogen, having about the same solubility as oxygen, and is best recognized by characteristic lines in the red end of the spectrum. Because of these lines it is used with neon in discharge tubes to produce a green-to-blue light for advertising signs, and it is used in argon-ion lasers.

Because of its inertness it is used in electric light bulbs and in fluorescent tubes (at a pressure of about 3 mm Hg), in photo tubes, glow tubes, and the tubes of geiger counters. In addition, it is used as an inert gas shield for arc welding and cutting, as a blanket to prevent oxidation during production of titanium and other reactive elements, and as a protective atmosphere for growing silicon and germanium crystals for use in semiconductor devices.