Which metal melts at about 29.8 °C, close to room temperature? Gallium does. Its melting point is 29.7646 °C, so a solid sample can melt in a warm room or in a person’s hand at about 37 °C.
Gallium is element 31, symbol Ga, and belongs to group 13, alongside aluminium and indium. French chemist Paul-Émile Lecoq de Boisbaudran discovered and isolated it in 1875. Its name comes from Gallia, the Latin name for France, rather than from its low melting point.
Gallium is unusual because it is solid under standard conditions but becomes liquid just above typical room temperature. Its unusual crystal structure helps explain its relatively low melting point compared with neighbouring metals. It also expands when it freezes, a property it shares with only a small number of substances.
The common mix-up is mercury: mercury is already liquid at ordinary room temperature, while gallium usually begins as a solid. Gallium is mainly used in electronics, including gallium arsenide and gallium nitride, which are important in high-speed circuits, LEDs and laser diodes.