Mercury, commonly known as quicksilver, is the chemical element with the symbol Hg and atomic number 80. It is the only metal that remains liquid at room temperature and standard pressure. It appears silvery-white, has a high density (approximately 13.5 g/cm3), a low melting point (around -38.8°C), and a boiling point of about 356.7°C. At room temperature, it evaporates, producing odorless, colorless mercury vapor.

Origin and Existence: Mercury primarily exists in nature as cinnabar (mercuric sulfide, HgS) and can be obtained through smelting. In the environment, mercury can migrate over long distances. Once it enters water bodies, it is converted into methylmercury by microorganisms and accumulates along the food chain.

Primary Uses: Historically employed in precision instruments such as thermometers, blood pressure gauges, and barometers; also used in the chlor-alkali industry for mercury cathodes, fluorescent lamps, batteries, switch relays, dental amalgam, and the "quenching method" for extracting gold and silver.