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Forget chocolate melting in your hands, try Gallium. Its a strange metal that has a melting point at 85 °F. Pick up a solid piece of gallium and squeeze it in your hand for a few minutes. Soon, you’ll have a liquid puddle of metal jiggling in your hand. Scientists love to show off experiments with Gallium. Set a drop on an aluminum can and watch it slowly turn the aluminum into brittle tissue paper. Set the stuff in sulfuric acid and you’ll see it start beating like a heart. Dmitri Mendeleyev first predicted Gallium and placed it in the Period Table before it was officially discovered in 1875.
Gallium is a chemical element with symbol Ga and atomic number 31. Elemental gallium does not occur in free form in nature, but as the gallium(III) compounds that are in trace amounts in zinc ores and in bauxite. Gallium is a soft silvery metal, and elemental gallium is a brittle solid at low temperatures. If it is held in the human hand long enough, gallium will melt, since it melts at the temperature of about 29.76 °C (85.57 °F) (slightly above room temperature). The melting point of gallium is used as a temperature reference point. The alloy galinstan (68.5% gallium, 21.5% indium, and 10% tin) has an even lower melting point of −19 °C (−2 °F), well below the freezing point of water. Beginning with its discovery in 1875 through the era of semiconductors, gallium was used primarily as an agent to make alloys that melt at low temperatures. Then, gallium became useful in semiconductors, including as a dopant.
Today, nearly all gallium is used in electronics. Gallium arsenide, the primary chemical compound of gallium in electronics, is used in microwave circuits, high-speed switching circuits, and infrared circuits. Gallium nitride and indium gallium nitride, minority semiconductor uses, produce blue and violet light-emitting diodes (LEDs) and diode lasers.
Gallium has no known role in biology. Because gallium(III) and ferric salts behave similarly in biological systems, gallium ions often mimic iron ions in medical applications. Some pharmaceuticals containing gallium and radiopharmaceuticals have been used rarely.