Gallium is the chemical element that melts in your hand because its melting point is about 29.8°C.
Gallium is a soft, silvery metal with the atomic number 31 and the symbol Ga. Its melting point is unusually low for a metal, just below normal human body temperature, although the exact experience depends on the object’s temperature and the surrounding conditions. It remains liquid across a wide temperature range before boiling at about 2,204°C.
The element was predicted by Dmitri Mendeleev in 1871, before it was discovered by French chemist Paul-Émile Lecoq de Boisbaudran in 1875. Its name comes from Gallia, the Latin name for France. Gallium is usually obtained as a by-product of processing bauxite and zinc ores rather than mined from a dedicated gallium deposit.
Gallium is not the only element that can be liquid near room temperature: mercury is already liquid at typical indoor temperatures, while cesium melts at about 28.5°C. Gallium is also notable because it expands as it freezes, so it should not be stored in a completely full glass container.