Transition metal, atomic number 80.
Mercury is a chemical element with symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum (/haɪˈdrɑːrdʒərəm/). A heavy, silvery d-block element, mercury is the only metallic element that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature.
Symbol Hg. Atomic mass 200.5923 u. Group 12, period 6. Electron configuration [Xe] 4f14 5d10 6s2. Electrons per shell 2, 8, 18, 32, 18, 2. State at room temperature: Liquid. Melting point -38.8 °C, boiling point 356.7 °C. Discovered by unknown, before 2000 BCE.
Element data from Wikipedia, CC BY-SA 3.0.