Gallium is a very easily liquefiable metal discovered, isolated, and soon studied by the French chemist Paul-Émile Lecoq de Boisbaudran (1875).
It is silvery white and soft enough to cut with a knife. Once liquefied, it exhibits the phenomenon of supercooling, being able to remain liquid even at 0°C; it remains liquid up to about 2000 C, and at 1500 C yet it still has a very low vapor pressure.
In its chemical properties, it is analogous to aluminum, with which it forms alums. It is not attacked by water at 100 C, but it is soluble in acids, forming trivalent compounds. It is an amphoteric metal giving gallates with alkaline bases with the production of hydrogen.
Gallium: Element Properties
|Melting point:||29.78 °C (85.6 °F)|
|Boiling point:||2,403 °C (4,357 °F)|
|Density (at 29.6° C):||5.904.|
Gallium is made as a by-product of the metallurgy of zinc, pyrites, bauxites and gemenite. The pure metal is obtained by electrolysis of the alkaline salts.
Uses of Gallium
Gallium is used as a dopant in semiconductors. Gallium arsenide (GaAs), isoelectronic of germanium (Ge), is capable of directly converting electricity into coherent light; it is used in light emitting diodes.
The compound MgGa2O4, of spinel type, activated by impurities made up of divalent ions such as Mn2+, is a phosphor emitting a brilliant green color during excitation in the ultraviolet, a color familiar to users of certain photocopiers.
Gallium is mainly used in alloying with arsenic in gallium arsenide GaAs, a semiconductor widely used in optoelectronics. This element also makes it possible to obtain images of areas of inflammation by scintigraphy in medical imaging.
Gallium health effects and toxicity
Gallium appears corrosive to the skin and mucous membranes, but is generally considered weakly toxic at doses encountered. However, it is seen that there are no comprehensive studies on the toxicology of this element for now.
First Image: Alshaer666, CC BY-SA 3.0, via Wikimedia Commons