The Westport Library Resource Guides: Gallium (Ga): Post-Transition Metals

What is Gallium?

Gallium (Ga), chemical element, metal of main Group 13 (IIIa, or boron group) of the periodic table. It liquefies just above room temperature. Gallium was discovered (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. Though widely distributed at Earth's surface, gallium does not occur free or concentrated in independent minerals, except for gallite, CuGaS₂, rare and economically insignificant. Continue reading from Encyclopedia Britannica

The History

Gallium was discovered in Paris by Paul-Émile Lecoq de Boisbaudran in 1875. He observed a new violet line in the atomic spectrum of some zinc he had extracted from a sample of zinc blende ore (ZnS) from the Pyrenees. He knew it meant that an unknown element was present. What Boisbaudran didn’t realise was that its existence, and properties, had been predicted by Mendeleev whose periodic table showed there was a gap below aluminium which was yet to be occupied. He forecast that the missing element’s atomic weight would be around 68 and its density would be 5.9 g/cm³. By November of 1875, Boisbaudran had isolated and purified the new metal and shown that it was like aluminium. In December 1875 he announced it to the French Academy of Sciences. Continue reading from Royal Society of Chemistry

Gallium Facts

Gallium has some very unique qualities. For example, although it is a solid at room temperature (about 77 F/ 22 C), it is still so soft that you could cut it with a knife. In addition, it has a low melting point of 85.57 F (29.76 C) — less than 10 degrees above room temperature — so if you were to pick up a lump of gallium, it would literally melt from the warmth of your hand. Then if you set it back down, it would solidify again. Liquid gallium cannot be kept in a glass or metal container because it expands 3.1 percent when it freezes. Continue reading from LiveScience