Gallium

Element Name: Gallium
Atomic Number: 31
Atomic Mass: 69.723
Atomic Symbol: Ga
Melting Point: 29.76° C
Boiling Point: 2204° C

Gallium is a silvery post-transition metal that is soft and glass-like. It was discovered in 1875 by the French chemist Paul E. Lecoq de Boisbaudran via spectroscope. It has poor metallic properties, as it is brittle and a poor conductor of electricity. Like Rubidium, Cesium, and Mercury, Gallium is a liquid near room temperatures. There are two stable isotope of Gallium (thus being 69Ga and 71Ga) and 22 other isotopes. Gallium has the property of expanding when it freezes, and it shares this property with Silicon, Bismuth, Antimony, and Germanium. Gallium readily alloys with most metals and is an ingredient in several low-melting alloys.

Interesting Facts:

The Russian chemist Mendeleev predicted the existence of Gallium (along with several of its properties) four years before it was detected. Gallium is named for Gallia, meaning Gaul (the ancient name for what is now France). Solid gallium fractures cochoidally (like the curves on a seashell). Gallium’s melting point is so low that it can melt in the human hand and then freeze again when let go. As a prank, a scientist served tea to his guest with Gallium spoons. They melted in the hot tea. It has the second longest liquid range of any element. Gallium expands when it freezes, similar to silicon, bismuth, antimony, and germanium. 98% of the gallium consumption in the U.S. in 2007 was in the forms of Gallium arsenide and gallium nitride.

Sources:

Gallium doesn’t exist in its elemental form in the earth’s crust. There’s approximately 17 parts per million in the crust, and is found in Gallite, bauxite, sphalerite, coal, diaspora, and germanite in small quantities. It is mainly obtained as the byproduct in the production of aluminum and zinc. Flue dust of coal also has some Gallium in it.

Industrial Uses:

Gallium is very lustrous when painted on glass, allowing it to be used as a mirror. Because it melts near room temperatures and changes volume as it melts, Gallium can be used to be thermostats, switches, barometers, and heating and cooling devices. Gallium’s most prominent use is in Gallium Arsenide, a semiconductor used for laser diodes, solar panels, and light-emitting diodes. Gallium arsenide makes up about 95% of the global gallium consumption. Alloying plutonium in the Sigma phase with gallium makes it machinable in the application of nuclear weapons. Gallium also sees some use in medicine. Gallium behaves like iron (III) while in the body, so if it’s taken up by bacteria it stops its respiration. The majority of its medical applications relies on its similarity to iron.

References:

“Gallium.” Chemicool Periodic Table. Chemicool.com, 17 Oct. 2012. Web. 26 July 2016.
“Gallium.” Wikipedia. Wikimedia Foundation, n.d. Web. 26 July 2016.
“Facts About Gallium.” Livescience. Livescience.com, 9 May 2013. Web. 26 July 2016.
“Gallium Facts Facts.” Softschools.com. N.p., n.d. Web. 26 July 2016.