Discovered | Name | Characteristics | Found | Uses

Gallium is a metal in the 4th period and in Group IIIA. Other elements in this group are boron (B), aluminum (Al), indium (In), and thallium (Tl).

Ga was discovered by Lecoq de Boisbaudran in 1875 when he observed two new spectral lines in zinc ores; in the same year, he isolated the free metal by electrolysis of a solution of gallium hydroxide in KOH. Starting with several hundred kilograms of zinc blende enriched in gallium, he isolated slightly more than one gram of gallium metal.

The name is derived from the Latin word, Gallia, for France and was given to the element by its discoverer, Lecoq de Boisbaudran. The symbol Ga is an abbreviation of the name.

The element and its properties were predicted by Mendeléev on the basis of his periodic table of elements. Mendeléev referred to the missing element as eka-aluminum.

Gallium is the only metal, except for mercury, cesium, and rubidium, that can be liquid near room temperatures (its melting point is 29.8°C). It has one of the longest liquid ranges of any metal and has a low vapor pressure even at high temperatures. Therefore it has been used in high-temperature thermometers.

Ultra-pure gallium has a silvery appearance and the solid metal exhibits a conchoidal fracture similar to glass. (Conchoidal fracture means breaking along lines that look like a cross section of a conch shell; that is, fracturing in curved lines.) The metal expands 3% on solidifying, resembling only two other substances (water and Bi) in this regard. Therefore, it should not be stored in glass containers as they may break as the metal solidifies.

Although widely distributed, the element does not occur in appreciable quantities, even in its richest ore, germanite. Gallium is found as a trace element in diaspore, sphalerite, germanite, bauxite, and coal.

Gallium has found recent use in doping semiconductors and producing solid-state devices, such as transistors. Gallium arsenide is capable of converting electricity directly into coherent light and is used in light-emitting diodes. Gallium readily alloys with most metals, and has been used as a component in low-melting alloys.