Gallium is a metal that can be in a liquid state at normal temperatures. It can be produced by smelting but is never found in pure form in nature. It has a silvery color and is listed among the so-called poor metals, since it has a very low durability even when in solid state. At normal room temperature, gallium starts to liquefy or melt, while in a colder environment it becomes very brittle. As a result, this element is not suited for most of the applications of the other common metals.
This element has the atomic number 31 in the periodic table. In very pure form, it has a very attractive silver color. It is normally available as an orthorhombic crystalline solid structure, with a bluish grey metallic hue.
Lecoq de Boisbaudran was the first chemist to discover gallium, while working on a sample of zinc blend that was extracted from the Pyrenees in 1875. He noticed two unknown purple lines in the ore spectrum, while examining it using a spectroscope. The periodic theory of Mendeleev, published several years earlier, predicted the existence of a number of undiscovered elements, and the features of the unknown metal in the sample matched the predictions. De Boisbaudran used a process of electrolysis to extract gallium from the zinc blend, as part of his experiments. His discovery was validated by other chemists and the new metal was given the atomic number 31 and the name gallium.
At low temperatures, gallium is a solid crystal. However, it lacks the structural strength of a real glass compound. It is very brittle and the crystals will actually shatter on their own if the temperature drops more. While lacking strength, gallium has excellent electrical properties as a semiconductor. It can greatly reduce the cost and performance of transistors and improves the effectiveness of diodes if included in their structure. Gallium has also been considered as a possible replacement for the silicon crystals used in the production of solar panels. It could greatly reduce the manufacturing costs, making alternative energy more sustainable.
Even if gallium is a poor metal in pure form, it can create strong alloys when combined with other elements, especially aluminum. This combination has special chemical properties and is able for example to separate the hydrogen from the oxygen in water. Gallium was also mixed with tin in order to create a liquid used as an experimental cooling agent that can control the temperature of high-performance computer chips. Modern medical thermometers are often based on a mix of gallium and iridium. One of the most common gallium compounds is the nitrate, which is used as a treatment for arthritis as part of both local creams and oral pills. Several high-tech dental technologies also consider the use of this metal.
Gallium is one of the few metals that are liquid at normal room temperatures and actually melts when touched. It is one of the heaviest liquids. Only three other metals, mercury, cesium and francium, share this very unusual chemical trait. Of all non-metallic elements, only bromine is liquid at normal temperatures around 30 degrees Celsius.
Another interesting property of gallium is that it actually expands in size when it turns solid, similar to water when it freezes. Only bismuth, antimony, germanium and silicon increase in size when solid.
While gallium ores are uncommon, the metal is often found as a by-product in ores such as zinc blend, germanite, bauxite or iron pyrite. When heated slightly or in contact with liquid metals like mercury, rubidium and cesium, gallium becomes a fluid. It can form brittle alloys when combined with other metals, decreasing their structural strength. It is investigated as a possible nuclear reactor heat exchange agent.
Since gallium alloys have a low melting point, they can be used to replace mercury in thermometers. Unlike mercury, gallium is not toxic, so it is safer to use.
A useful semiconductor needed for the production of solar panels and both laser and light-emitting diodes is gallium arsenide. It reflects light, so it is also used in mirrors. It has various other uses, in the manufacturing of mobile phones, touch switch pressure sensors, Blue-ray technology, as well as blue and green LEDs. Another derivate of gallium with special semiconductor properties is its nitride.
Gallium is also an essential element for the production of smart phones. It is not present in pure form in their structure, but as part of a chemical compound known as gallium arsenide. This compound has many uses in the manufacturing industry, due to its special properties. It can transform electrical power into light, so smart phones need it for their LED lights. For the same reason, it is widely used in many other electronic devices.
When applied on glass or porcelain, liquid gallium acts like a coating and created a very reflective and bright surface. This makes it very easy to produce quality mirrors. Gallium is also easy to alloy with other metals, reducing their melting point. A gallium alloy is used to stabilize the allotropes of plutonium as part of the plutonium pits of nuclear bombs.
In industry, the main gallium application is the production of analog integrated circuits, which still have many uses. Big amounts are also needed in optoelectronic devices such as LEDs and laser diodes. This metal is a natural semiconductor and the compound gallium arsenide offers the best properties. It is found in many electronic displays and watches because it can convert electricity into light.
Pure gallium is never found in nature. While some compounds do exist, there are not usually used to extract this metal. Even if gallium is naturally more abundant than lead, it is considerably more difficult to produce. This is because of its wide dispersion, unlike lead that was concentrated into minerals by various geological processes. There are some types of coal that can be rich in gallium and it is also found in the ores of other metals, especially bauxite.
The characteristics of gallium make it suitable for a number of special purposes. It helps detect neutrinos when used in telescopes and it can turn plutonium into a stable form that can be machined for nuclear weapons. Modern thermometers use an alloy named galinstan, which consists of gallium, indium and tin and is safer than the classic mercury. Gallium is also a candidate to replace mercury in dental medicine. This special metal is also needed for solar panel manufacturing.
The gallinstan alloy has a special chemical property: when applied to aluminum it triggers a reaction with water that releases hydrogen. Some gallium compounds are also used as medication, for example in order to reduce the blood calcium content. Some types of nuclear medicine use radioactive gallium isotopes in the scanning process.
The human body naturally includes gallium, but only in a trace amount. There are for example only 0.7 milligrams of this metal in the body of a normal person with a weight of 70 kilograms. This is an extremely low amount, compared with most other metals.
Scientists have not been able to identify any role of gallium in the body functions. It doesn't seem to provide any benefits and the trace amount found is most likely ingested from water, fruits and vegetables. The metal has been detected in very low concentrations in some brands of bottled water, as well as several vitamins and supplements. Unlike other liquid metals, gallium can be touched without any toxic effects. Some people actually enjoy handling it, because the natural heat of the human hand is enough to make it melt. It must be noted however that it stains the hands when handled.
Gallium citrate is a radioactive compound that doesn't harm the human body at all. It can be used for scanning and injected without any kind of negative effects. Gallium should not however be ingested in large amounts, even if it is known to be safe in small ones. There are a number of gallium compounds known to be extremely toxic. Gallium chloride is dangerous even in small amounts and irritates the throat, with chest pain and difficult breathing. Inhaling a significant amount of fumes can cause paralysis, pulmonary edema and other very serious problems.