Periodic Table


Atomic number: 80
Atomic weight: 200.59
Symbol: Hg
Group number: 12
Electronic configuration: [Xe].4f14.5d10.6s2


Mercury is the only common metal liquid at ordinary temperatures. Mercury is sometimes called quicksilver. It only rarely occurs free in nature and is found mainly in cinnabar ore (HgS) in Spain and Italy. It is a heavy, silvery-white metal; a rather poor conductor of heat, as compared with other metals, and a fair conductor of electricity. It forms alloys easily with many metals, such as gold, silver, and tin, and these alloys are called amalgams. Its ease in amalgamating with gold is made use of in the recovery of gold from its ores.

The most important salts are mercuric chloride HgC12 (corrosive sublimate - a violent poison), mercurous chloride Hg2Cl2 (calomel, occasionally still used in medicine), mercury fulminate (Hg(ONC)2, a detonator used in explosives), and mercuric sulphide (HgS, vermillion, a high-grade paint pigment). Organic mercury compounds are important - and dangerous. Methyl mercury is a lethal pollutant found in rivers and lakes. The main source of pollution is industrial wastes settling to the river and lake bottoms.

Mercury is a virulent poison and is readily absorbed through the respiratory tract, the gastrointestinal tract, or through unbroken skin. It acts as a cumulative poison since there are few pathways available to the body for its excretion. Since mercury is a very volatile element, dangerous levels are readily attained in air. Air saturated with mercury vapour at 20°C contains a concentration that exceeds the toxic limit many times. The danger increases at higher temperatures. It is therefore important that mercury be handled with care. Containers of mercury should be securely covered and spillage should be avoided. Mercury should only be handled under in a well-ventilated area. If you are in possession of any mercury you are advised to take it to a properly qualified chemist for its safe disposal.

General information

Discoveror: Known since ancient times
Date discovered:
Discovered at: not known
Meaning of name: Named after the planet "Mercury" (the origin of the symbol Hg is the Latin word "hydrargyrum" meaning "liquid silver")

Physical data

Standard state: liquid (the heaviest known elemental liquid)
Colour: silvery white
Density of solid at ambient temperature/kg m-3: no data
Molar volume/cm3: 14.09

Radii /pm

Atomic: 171
Covalent (single bond):
Pauling radius for the ion [Hg]-: no data

Valence shell orbital radius maxima (Rmax)
orbital s p d f
radius141.7no data60.819.2


Both values are quoted on the Pauling scale.

Pauling: 2.00
Allred Rochow: 1.44

Crystal Structure

structure: rhombohedral

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.


Temperatures (/K)

melting point: 234.32
boiling point: 629.88

Enthalpies /kJ mol-1

fusion: 2.29
vaporization: 59.2

single bond enthalpies:
Hg-F Hg-Cl Hg-Br Hg-I Hg-Hg
no data no data no data no data 8

Ionization enthalpies /kJ mol-1

Number Enthalpy


This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance
196Hg195.965807 (5)0.15 (1)
198Hg197.966743 (4)9.97 (8)
199Hg198.968254 (4)16.87 (10)
200Hg199.968300 (4)23.10 (16)
201Hg200.970277 (4)13.18 (8)
202Hg201.970617 (4)29.86 (20)
204Hg203.973467 (5)6.87 (4)

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Hg.html