Gallium is a chemical element with the symbol Ga and atomic number 31. Elemental it is a soft, silvery blue metal at standard temperature and pressure; however in its liquid state it becomes silvery white. If too much force is applied, The Ga may fracture conchoidally. It is in group 13 of the periodic table, and thus has similarities to the other metals of the group, aluminium, indium, and thallium. It does not occur as a free element in nature, but as gallium(III) compounds in trace amounts in zinc ores and in bauxite.
It was discovered in 1875 by French chemist Paul-Émile Lecoq de Boisbaudran, who observed its principal spectral lines while examining material separated from zinc blende. Soon afterward he isolated the metal and studied its properties, which coincided with those that Russian chemist Dmitry Ivanovich Mendeleyev had predicted a few years earlier for eka-aluminum, the then-undiscovered element lying between aluminum and indium in his periodic table.
Characteristics of Gallium
- It is silvery white and soft enough to be cut with a knife. It takes on a bluish tinge because of superficial oxidation. Unusual for its low melting point (about 30 °C [86 °F])
- It also expands upon solidification and supercools readily, remaining a liquid at temperatures as low as 0 °C (32 °F). Ga remains in the liquid phase over a temperature range of about 2,000 °C, with a very low vapour pressure up to about 1,500 °C, the longest useful liquid range of any element.
- The liquid metal clings to (wets) glass and similar surfaces. The crystal structure of gallium is orthorhombic.
- Natural gallium consists of a mixture of two stable isotopes: gallium-69 (60.4%t) and gallium-71 (39.6%).
- Gallium has been considered as a possible heat-exchange medium in nuclear reactors, although it has a high neutron-capture cross section.
- Elemental gallium is a liquid at temperatures greater than 29.76 °C, above room temperature, but below the normal human body temperature of 37 °C. Hence, the metal will melt in a person’s hands.