On the periodic table, the element with the chemical symbol Hg, from the Latin name hydrargyrum, is mercury.
Mercury is a metallic element with atomic number 80. The Latin-derived name hydrargyrum means “liquid silver,” which explains the symbol Hg. Mercury is a transition metal in group 12 and is notable for being liquid at ordinary room temperature.
Its low melting point allowed mercury to be used historically in thermometers, barometers, switches, and scientific instruments. Many of these applications have declined because mercury and its compounds are toxic and can persist in the environment. Exposure risks depend on the chemical form and route of contact.
Mercury is sometimes confused with gallium, which can also melt near room temperature, but gallium is solid at typical room temperature and has a different symbol, Ga. Mercury’s liquid state is a physical property, while Hg is a historical-language clue in its chemical symbol.