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Gallium–the wonder metalAdd to favourite

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Description and discovery

Gallium is an artificial chemical element, which does not exist in nature in its free form.A few years before it was even discovered, its existence and properties were predicted by Dmitri Mendeleev, the Russian chemist whose name became attached to the periodic table of the elements.

 Gallium, metals that are liquid, wonder metal, Paul E. Lecoq, nuclear weapons, silver-colored metal, crystalline structure

He named this hypothetical, would-be element ”eka-aluminum” and predicted it would sit right below aluminum on the periodic table. In 1875, French chemist Paul E. Lecoq de Boisbaudran discovered the new element through a spectroscope, and identified it as a new element due to its characteristic spectrum indicating two violet lines.

It was named after Gallia, the Latin name for France, the land of its discovery, but rumor has it that the name is also a reference to the discoverer’s name.

Gallus also means 'rooster' in Latin, or Le Coq in French, but the scientist has later denied in an article that he named the element after himself. De Boisbaudran first extracted gallium from a zinc blende ore originating in the Pyrenee Mountains, and initially only obtained 0.65 grams from 430 kilograms of ore. He isolated the metal using electrolysis of its hydroxide in potassium hydroxide solution. Gallium is a byproduct of the process of producing aluminum and zinc, and most of it is currently extracted from the crude aluminum hydroxide solution of the Bayer process for producing alumina and aluminum.

 

Gallium metal expands by 3.1% when it returns to solid state, so storage in either glass or metal containers is to be avoided, since there is a risk that the container can rupture with freezing. In its liquid state, gallium shares the high density that only a few other materials have - silicon, germanium, bismuth and water. It is also important to mention that gallium attacks most other metals.

 
Gallium, metals that are liquid, wonder metal, Paul E. Lecoq, nuclear weapons, silver-colored metal, crystalline structure

Gallium is a soft, silver-colored metal with a crystalline structure, and along with cesium, rubidium and mercury and francium, it is one of the metals that are liquid at or near-normal room temperature. Its melting point is about 29.76 °C (85.57 °F), which is just slightly higher than room temperature, and can literally melt in your hand if you hold it long enough, and then it refreezes if you remove it. Bearing spectacular properties just like mercury does, but without its toxicity, it is no surprise that it became a popular curiosity, lots of people often buying it for entertainment, just as they would buy silly putty, and to hundreds of home-made “science videos” on YouTube One classic prank born among scientists involves gallium spoons – when they are used to serve tea to unsuspecting guests, they melt in the heat, offering a good dose of shock and awe.

 

However, this silver-looking metal is capable of so much more than practical jokes. No role in biology has been identified for gallium so far, but it has been discovered that its ion can localize and interact with certain processes in the human body that involve iron (III).

 

These processes typically include inflammation, which is a sign of many diseases, so this curious element has found its use even in medicine. Some gallium-67 salts like gallium citrate or gallium nitrate are often used to act as radiopharmaceutical agents in a nuclear imaging procedure known as a ”gallium scan”. The body handles these compounds very much like it would handle iron, but the localization of gallium in the human body has some unique properties – rapidly concentrating in areas of inflammation, such as infection, or in areas of rapid cell division, gallium helps diagnosis through nuclear scan techniques.

Gallium nitrate, branded with the name Ganite by its manufacturers, is often used intravenously to treat hyperkalemia associated with tumor metastasis to bones, and studies show it could be effective when other treatments for malign hyperkalemia are not. An orally-absorbable form of galium (III), gallium maltolate, is currently in trials, believed to be a potential treatment for several types of cancer and infectious or inflammatory disease such as cystic fibrosis. Moreover, a complex compound of gallium (III) was discovered to be toxic to certain parasites.

 

At the University of Washington, researchers claim to have found a new way to fight and beat the more and more drug-resistant bacteria, trying to aid the body's natural defense systems against them. The senior author of the study, Pradeep Singh, is an associate professor of medicine and microbiology at the university, and as he explained, the key battle between the foreign bacteria and the human body is for iron.

 

So basically the cells defending our organism struggle to keep the iron safe away from bacteria as it tries to “steal” it. The similarity of iron and gallium gave scientists the idea to build a form of Trojan horse based on gallium to lure the bacteria in, tricking them to feed on an element that cannot help them survive. At the end of the 19th century when gallium was discovered, its first use was in high-temperature thermometric applications and for alloy making, since it had two important properties – stability and an ease of melting.

 

 

Its primary chemical compound is gallium arsenide, developed in the 1960s, which opened the door for an even wider list of applications. Nowadays, almost all gallium is being used in electronics, and gallium arsenide can often be found in microwave circuits, high-speed switching circuits, infrared circuits, ultra-high speed logic chips or low-noise microwave preamplifiers in cell phones.

 
Blue Light Gallium LED

Gallium nitride and indium gallium nitride are used to produce blue and violet light-emitting diodes (LEDs), while and aluminum gallium arsenide (AlGaAs) is used in high-powered infrared laser diodes, and this is why gallium has now come to be commercially available in extremely high-purity (99.9999+%). One particular use for gallium nitride for example is producing a violet light source for higher-density data storage in the Blu-ray DVDs.

Its use in low-melting alloys and its mainly liquid state have also made it a likely candidate for use in medical thermometers. An alloy named Galinstan has an exceptionally low freezing point of only −19 °C (−2.2 °F), and researchers have suggested that this particular alloy could also be used for cooling computer chips.

Gallium wets glass or porcelain, so another use for it can be to create brilliant mirrors. However, when this effect is not desired, the glass must be protected with a transparent layer of gallium (III) oxide.

Due to its ability to alloy easily with other metals, gallium is sometimes used the in small quantities for nuclear weapons: when used in the form of plutonium-gallium alloy in the plutonium cores of nuclear bombs, it can help stabilize the crystal structure of plutonium.

Gallium arsenide has also found its utility in the photovoltaic cells designed for satellite power applications, now being used in the Mars Exploration Rovers and various satellites. On a more down-to-Earth note, Gallium is also found in photovoltaic compounds used in solar panels, offering a less costly alternative to crystalline silicon.

 

The curious world of particle physics also seems to be reaping the advantages of this metal. The SAGE solar neutrino experiment for neutrino detection has gathered possibly the largest amount of pure gallium ever collected in a single spot. The Gallium-Germanium Neutrino Telescope used at the Baksan Neutrino Observatory in Russia contains 55–57 tons of liquid gallium. The exceptional feature of this experiment is the capability to detect low-energy neutrinos from proton-proton fusion.

 

This is the only way that neutrinos, produced in the primary reaction that provides the Sun's energy and the major component of the solar neutrino flux, have been ever observed so far.

Another similar experiment was conducted in the 1990s in Italy, using 12.2 tons of watered gallium-71 in the neutrino detector called GALLEX. Solar neutrinos caused a number of 71Ga atoms to become radioactive 71Ge, which were able to be detected.

 

 

Interesting facts

  • Gallium nitride is producing a violet light source for higher-density data storage in the Blu-ray DVDs.
  • Due to its ability to alloy easily with other metals, gallium is sometimes used the in small quantities for nuclear weapons
  • Gallium was discovered by French chemist Paul E. Lecoq de Boisbaudran, and identified it as a new element due to its characteristic spectrum indicating two violet lines; It was named after Gallia, the Latin name for France
  • Is one of the metals that are liquid at or near-normal room temperature? Its melting point is about 29.76 °C (85.57 °F)

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Sources:
https://en.wikipedia.org/wiki/Gallium
http://minerals.usgs.gov/minerals/pubs/commodity/gallium/mcs-2013-galli.pdf
http://www.infoniac.com/health-fitness/trojan-gallium.html
http://ewi.npl.washington.edu/sage/
http://lappweb.in2p3.fr/neutrinos/anexp.html#gallex
http://chemistry.about.com/od/elementfacts/a/gallium.htm
http://www.lenntech.com/periodic/elements/ga.htm
http://www.chemicool.com/elements/gallium.html
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