Symbol Hg A silvery-white, dense, poisonous metallic element that is a liquid at room temperature and is used in thermometers, barometers, batteries, and pesticides. Atomic number 80; atomic weight 200.59; melting point -38.87°C; boiling point 356.58°C; specific gravity 13.546 (at 20°C); valence 1, 2. See
Periodic Table.
Like a few other elements, mercury has a chemical symbol, Hg, that bears no resemblance to its name. This is because Hg is an abbreviation of the Latin name of the element, which was
hydrargium. This word in turn was taken over from Greek, where it literally meant “water-silver.” With this name the Greeks were referring to the fact that mercury is a silvery liquid at room temperature, rather than a solid like other metals. Similarly, an older English name for this element is
quicksilver, which means “living silver,” referring to its ability to move like a living thing. (The word
quick used to mean “alive,” as in the Biblical phrase “the quick and the dead.”) The name
mercury refers to the fact that the element flows about quickly: the name comes from the Roman god Mercury, who was the swift-footed messenger of the gods.