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.
Three reasons Mercury stands out
- 1
Liquid at room temperature, historically used in thermometers.
- 2
It accumulates up the food chain, which is why large predatory fish like swordfish carry significant levels of it.
- 3
It was used in the world's first barometers in the 17th century to measure atmospheric pressure.
The restless liquid metal
Mercury is liquid at room temperature because its electrons bind the atoms together less effectively than expected for a heavy metal. That mobility made precise thermometers and barometers possible, but mercury vapor and methylmercury attack the nervous system. Modern controls reflect a hard-earned toxicological history.