Mercury, the metal whose elemental name of Hg gets its Latin roots from the word hydragyrum, meaning "liquid silver," is the only metal that's a liquid at room temperature. Also known as quicksilver, mercury is one of only a handful of metals known since antiquity, and it can be found in several surviving ancient sites and historical texts. But since it also sits squarely on the modern periodic table in the center of a block of metallic elements that are solid at room temperature, its liquid state might seem like something of a puzzle.
The reason mercury manages to be a liquid at room temperature is because its bonding structure is weaker than that of most metals. The electrons that spin around mercury nuclei don't easily maintain linkages with other mercury atoms at standard temperatures, hence the lack of solidity [source: Senese]. Mercury is also something of an oddity for another reason, considering where it sits on the periodic table: The elements around it are much better at conducting heat and electricity.
Its liquid form makes mercury is a very versatile element, however. It conducts electricity and is used in switches, and it's also in barometers and thermometers. It can also be combined with a variety of other metals. Mercury on its own is poisonous, and when combined with other elements, it can form different compounds, which are used in everything from antiseptics and pesticides to batteries, fluorescent lamps and detonators for explosives [source: Jefferson Lab].
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