On the periodic table, gallium melts at about 29.76 °C.
Gallium has the symbol Ga and atomic number 31. Since its melting point is just above typical room temperature, a piece held in a warm hand can melt. It freezes at about 29.76 °C as well, although gallium can remain liquid below its freezing point because it is prone to supercooling.
Dmitri Mendeleev predicted gallium’s existence and properties in 1871, calling the unknown element eka-aluminium. French chemist Paul-Émile Lecoq de Boisbaudran discovered it in 1875 using spectroscopy and later isolated it.
Gallium is a post-transition metal and is used in compounds such as gallium arsenide, an important semiconductor material. Indium and bismuth are neighboring metals with different melting points, so the hand-melting clue specifically identifies gallium.