Mercury - Hg

Symbol Hg
Atomic Number 80
Atomic Mass 200.59 g.mol -1
Discovered by The Ancients

What is Mercury?

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.

As a chemical element, mercury cannot be created or destroyed. The same amount has existed on the planet since the earth was formed. Mercury, however, can cycle in the environment as part of both natural and human activities. Mercury metal also found many new applications in electrical devices and electrochemistry. Mercury metal is a volatile liquid; it has a measurable vapor pressure at room temperature.

The density of mercury is 13.6 at 20°C


Element 80: Mercury


Electronegativity according to Pauling 1.9
Density of mercury 13.6 at 20°C
Melting point of mercury – 38.9 °C
Boiling point of mercury 356.6 °C
Van Der Waals radius 0.157 nm
Ionic radius of mercury 0.11 nm (+2)
Isotopes or mercury 12
Electronic shell of mercury [ 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 of mercury + 0.854 V ( Hg2+/ Hg )

Mercury element 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 vapour when heated; later the vapour is cooled and captured as liquid mercury.

Mercury metal

Representation of mercury metal

Some of the 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

Mercury element in the periodic table is symbolized as Hg.

Mercury Physical properties

Mercury metal can be frozen changed into a solid at a temperature of –38.85°C. It can be transformed into a gas when boiled at 365.6°C. The density of mercury is 13.59 grams per cubic centimetre.

It has two physical properties of special interest.

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

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 applications. Because of its high-density mercury 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.

Frequently asked questions

1. Mercury is also known as _______.

Ans: Quicksilver.

2. What is the symbol used to represent mercury element?

Ans: Hg.

3. What is the atomic number of mercury?

Ans: 80.

4. What is the boiling and melting point of mercury?

Ans: The boiling point of mercury is 356.6 °C and its melting point is – 38.9 °C.

5. List two uses of mercury element.

Ans: It is used in insecticides and skin ointments.

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