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80Hg200.59

Element 80, a transition metal

Mercury

The only metal that is liquid at room temperature: quicksilver to the alchemists, and a toxic pollutant today.

At a glance

Symbol
Hg
Atomic number
80
Average atomic mass
200.59
Group
12
Period
6
Family
transition metal
Electron configuration
[Xe] 4f¹⁴ 5d¹⁰ 6s²
Electronegativity
2.00
Common ions
Hg²⁺, and the paired ion Hg₂²⁺ in mercury(I) compounds

On the table

Periodic table with Mercury highlighted123456789101112131415161718123456757-7189-103HHeLiBeBCNOFNeNaMgAlSiPSClArKCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRnFrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgCnNhFlMcLvTsOg

Period 6, group 12. The other transition metals are tinted, and every cell opens its own article.

Electrons and bonding

Mercury holds its two 6s electrons so tightly that its atoms bond only weakly to one another, which is why it is a liquid. In compounds it forms Hg²⁺ or the unusual paired ion Hg₂²⁺.

Properties

State at 25 °C
liquid
What it looks like
shiny, silvery liquid metal
Melting point
−38.8 °C
Boiling point
356.7 °C
Density
13.5 g/cm³

Where it is found

Mined almost entirely as cinnabar (HgS), a red mineral. The mine at Almadén in Spain produced mercury for about 2,000 years; today China produces most of it.

Discovery and name

Known since ancient times; mercury has been found in Egyptian tombs from around 1500 BCE. It is named after the Roman messenger god and the planet, and the symbol Hg comes from its Latin name hydrargyrum, water-silver.

What it is used for

Once common in thermometers, barometers and blood pressure gauges, and still used in some fluorescent lamps and industrial processes. Dental amalgam fillings contain it. Small-scale gold miners use it to extract gold, now the largest source of mercury pollution.

In compounds

HgScinnabar, vermilion pigmentHgCl₂mercury(II) chlorideHg₂Cl₂mercury(I) chloride, calomelCH₃Hg⁺methylmercury, builds up in fish

Handle with care

Mercury vapor and mercury compounds damage the nervous system and kidneys. Methylmercury builds up in fish, and in the 1950s mercury waste dumped into Minamata Bay in Japan poisoned thousands of people. Spilled mercury should never be vacuumed.