Mercury is the only metallic element that is a liquid at room temperature. This dense metal is atomic number 80 with the element symbol Hg. Mercury derives its name from the association between the planet Mercury and its use in alchemy. The alchemical symbol for mercury was the same for the metal and the planet. The element symbol, Hg, is derived from the Latin name 'hydragyrum' meaning "water silver".

Source: ThoughtCo