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Portrait of Mercury

Science · Chemistry

Mercury

Chemistry — transition metals

Mercury is element 80, the only metal that is liquid at ordinary room temperature and pressure, freezing only at −38.83 °C. Known since antiquity and found in tombs from the second millennium BC, it was called quicksilver — living silver — and named for the swift Roman god and his planet. Its symbol Hg comes from hydrargyrum, the Latinised Greek for "water-silver". Prized for centuries in barometers, thermometers, gilding and medicine, it is now known to be a potent neurotoxin, and its use is being wound down worldwide under the 2013 Minamata Convention.

How to spot them

  • ▸The only metal that is liquid at standard temperature and pressure
  • ▸Symbol Hg, from a Latin word meaning 'water-silver'
  • ▸Its chief ore is the brilliant red cinnabar
  • ▸Barometers, old thermometers, gilding, felt hats and Minamata Bay
  • ▸The 'quick' in its old English name means living, not fast

Key facts

Symbol Hg, from the Latin hydrargyrum, 'water-silver'

Via the Greek hydrargyros, coined for a metal that flows like water yet shines like silver

The only metal that is liquid at room temperature, freezing at −38.83 °C

Bromine is the only other element liquid under standard conditions, and it is a non-metal

Its old English name means 'living silver'

Quicksilver — 'quick' in the archaic sense of alive, as in 'the quick and the dead'

Torricelli's 1643 barometer used a column of it about 760 mm high (1643)

Its density made a manageable tube possible, where water would have needed over ten metres

Poisoning from its nitrate in felt-making gave English 'mad as a hatter'

Hatters exposed to mercuric nitrate developed tremors, slurred speech and delusions

An industrial discharge into a Japanese bay gave a crippling disease its name

Minamata disease, from methylmercury dumped by the Chisso plant from the 1930s

Named after the swiftest planet and the winged messenger of the Roman gods

Its alchemical symbol is the same as the planet's

Key ideas

  • Relativistic contraction of the 6s electrons makes them unusually tightly held, weakening metallic bonding and leaving the metal liquid at room temperature
  • Inorganic mercury is methylated by bacteria into methylmercury, which then bioaccumulates up the food chain into large predatory fish

Quick-fire facts

  • •Atomic number 80; symbol Hg from hydrargyrum, itself from Greek hydrargyros, 'water-silver'
  • •Melting point −38.83 °C, boiling point 356.7 °C; density 13.53 g/cm³, so lead and iron float on it
  • •One of the seven metals known to antiquity, alongside gold, silver, copper, iron, tin and lead; found in Egyptian tombs of about 1500 BC
  • •Its principal ore is cinnabar, mercury(II) sulfide, the source of the pigment vermilion; the Almadén mine in Spain worked it for two millennia
  • •Evangelista Torricelli invented the mercury barometer in 1643; Daniel Fahrenheit made the first mercury-in-glass thermometer in 1714
  • •Mercury fulminate was the detonator in percussion caps; calomel (mercury(I) chloride) was a standard purgative
  • •The Minamata Convention on Mercury, agreed in 2013 and in force from 2017, phases out mercury in most products and processes
  • •Mercury-vapour discharge gives fluorescent lamps their ultraviolet light; dental amalgam is roughly half mercury by weight
  • •The Mad Hatter of Alice in Wonderland is usually linked to hatters' mercury poisoning, though Carroll never says so

Drill it — 9 cards

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Sources