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Jai Ganesh

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Gallium

Gallium

Gist

Gallium is a chemical element; it has symbol Ga and atomic number 31. Discovered by the French chemist Paul-Émile Lecoq de Boisbaudran in 1875, elemental gallium is a soft, silvery metal at standard temperature and pressure. In its liquid state, it becomes silvery white.

Gallium is a foundational element in the semiconductors that power LED backlighting in smartphone displays. Gallium nitride (GaN), in particular, underpins the blue and ultraviolet LEDs that drive white backlight units in LCD screens.

Gallium is a soft, silvery-white metallic element with a low melting point, making it liquid at near room temperature. It's known for its ability to wet glass and its use in various electronic components.

Summary

Gallium is a chemical element; it has symbol Ga and atomic number 31. Discovered by the French chemist Paul-Émile Lecoq de Boisbaudran in 1875, elemental gallium is a soft, silvery metal at standard temperature and pressure. In its liquid state, it becomes silvery white. If enough force is applied, solid gallium may fracture conchoidally. Since its discovery in 1875, gallium has widely been used to make alloys with low melting points. It is also used in semiconductors, as a dopant in semiconductor substrates.

The melting point of gallium, 29.7646 °C (85.5763 °F; 302.9146 K), is used as a temperature reference point. Gallium alloys are used in thermometers as a non-toxic and environmentally friendly alternative to mercury, and can withstand higher temperatures than mercury. A melting point of −19 °C (−2 °F), well below the freezing point of water, is claimed for the alloy galinstan (62–95% gallium, 5–22% indium, and 0–16% tin by weight), but that may be the freezing point with the effect of supercooling.

Gallium does not occur as a free element in nature, but rather as gallium(III) compounds in trace amounts in zinc ores (such as sphalerite) and in bauxite. Elemental gallium is a liquid at temperatures greater than 29.76 °C (85.57 °F), and will melt in a person's hands at normal human body temperature of 37.0 °C (98.6 °F).

Gallium is predominantly used in electronics. Gallium, the primary chemical compound of gallium in electronics, is used in microwave circuits, high-speed switching circuits, and infrared circuits. Semiconducting gallium nitride and indium gallium nitride produce blue and violet light-emitting diodes and diode lasers. Gallium is also used in the production of artificial gadolinium gallium garnet for jewelry. It has no known natural role in biology. Gallium(III) behaves in a similar manner to ferric salts in biological systems and has been used in some medical applications, including pharmaceuticals and radiopharmaceuticals.

Details

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. It is extracted as a by-product from zinc blende, iron pyrites, bauxite, and germanite.

Gallium 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]), gallium also expands upon solidification and supercools readily, remaining a liquid at temperatures as low as 0 °C (32 °F). Gallium remains in the liquid phase over a temperature range of about 2,000 °C (about 3,600 °F), with a very low vapour pressure up to about 1,500 °C (about 2,700 °F), 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 percent) and gallium-71 (39.6 percent). Gallium has been considered as a possible heat-exchange medium in nuclear reactors, although it has a high neutron-capture cross section.

The metal gallium is stable in dry air. Somewhat similar to aluminum chemically, gallium slowly oxidizes in moist air until a protective film forms. On burning in air or oxygen, it forms the white oxide Ga2O3. This oxide can be reduced to the metal when heated at high temperatures in hydrogen, and with gallium metal at 700 °C (1,300 °F), it gives the lower oxide Ga2O. It does not dissolve in cold nitric acid, because, as with moist air, a protective film of gallium oxide forms. Gallium does not react with water at temperatures up to 100 °C (212 °F) but reacts slowly with hydrochloric and other mineral acids to give the gallium ion, Ga3+. The metal does dissolve in other acids to give gallium salts, and it dissolves in alkalies, with the evolution of hydrogen, to give gallates, such as [Ga(OH)4]−, in which gallium appears in the anion. Gallium is amphoteric (i.e., it reacts either as an acid or as a base, depending on the circumstance), reacting with sodium and potassium hydroxide solutions to yield a gallate and hydrogen gas. The halogens attack it vigorously.

Element Properties

atomic number  :  31
atomic weight  :  69.723
melting point  :  29.78 °C (85.6 °F)
boiling point  :  2,403 °C (4,357 °F)
specific gravity  :  5.904 (at 29.6 °C [85.3 °F])
oxidation state  :  +3.

Additional Information:

Appearance

Gallium is a soft, silvery-white metal, similar to aluminium.

Uses

Gallium has a similar structure to silicon and is a useful silicon substitute for the electronics industry. It is an important component of many semiconductors. It is also used in red LEDs (light emitting diodes) because of its ability to convert electricity to light. Solar panels on the Mars Exploration Rover contained gallium math.

Gallium nitride is also a semiconductor. It has particular properties that make it very versatile. It has important uses in Blu-ray technology, mobile phones, blue and green LEDs and pressure sensors for touch switches.

Gallium readily alloys with most metals. It is particularly used in low-melting alloys.

It has a high boiling point, which makes it ideal for recording temperatures that would vaporise a thermometer.

Biological role

Gallium has no known biological role. It is non-toxic.

Natural abundance

It is present in trace amounts in the minerals diaspore, sphalerite, germanite, bauxite and coal. It is mainly produced as a by-product of zinc refining.

The metal can be obtained by electrolysis of a solution of gallium(III) hydroxide in potassium hydroxide.

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