Element 80: Mercury

Atomic number 80
Atomic mass 200.59 g.mol -1
Electronegativity according to pauling 1.9
Density 13.6 at 20°C
Melting point – 38.9 °C
Boiling point 356.6 °C
Van Der Waals radius 0.157 nm
Ionic radius 0.11 nm (+2)
Isotopes 12
Electronic shell [ Xe ] 4f14 5d10 6s2
Energy of first ionisation 1004.6 kJ.mol -1
Energy of second  ionisation 1796 kJ.mol -1
Energy of third ionisation 3294 kJ.mol -1
Standard potential + 0.854 V ( Hg2+/ Hg )
Discovered The Ancients

Mercury is a chemical element and the only common metal which is liquid at ordinary temperatures. It is commonly known as quicksilver and is heavy, silvery-white liquid metal. Mercury is a transition metal, where one of the elements found between Group 2 (IIA) and 13 (IIIA) on the periodic table.

It has been known for thousands of years. People learned to make this metal from the most important ore called Cinnabar. The cinnabar releases mercury as a vapor when heated, later the vapor is cooled and captured as liquid mercury.


Some of mercury compounds are known to be poisonous such as mercuric chloride – corrosive sublimate – is used to kill pests. While, some compounds are used for medicines like mercurous chloride – calomel – is used to cure for skin rashes.

Symbol of Mercury in Periodic Table

This metal in periodic table is symbolized as Hg.

Mercury Physical properties

Mercury can be frozen changed into a solid at a temperature of –38.85°C. It can be changed into a gas when boiled at 365.6°C. Its density is 13.59 grams per cubic centimeter.

It has two physical properties of special interest.

  • Very high surface tension.
  • Very good conductor of electricity.

The Surface tension is a property of liquids that makes them act like they are covered with skin. While, being a good conductor of electricity, this property is used in a mercury switch kind of turns light on and off.

Mercury Chemical Properties

Mercury is moderately active. It does not react with oxygen in the air. It reacts with some acids when they are hot, but not with most cold acids.

Uses of Mercury

Mercury metal has many uses. Because of its high density it is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices.

The mercury compounds have many uses:

  • The Calomel – mercurous chloride ( Hg2Cl2 ) is used as a standard in electrochemical measurements and in medicine as a purgative.
  • The mercuric chloride – corrosive sublimate ( HgCl2 ) is used as the insecticide such as rat poison and disinfectant.
  • The Mercuric oxide is used in skin ointments.
  • Mercuric sulphate is used as a catalyst in organic chemistry.

Practise This Question

____ is a transportation system that carries sewage from the point of production to the point of disposal.

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