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

Mercury is a liquid metallic element of many useful applications. It is also an element with properties hazardous to the environment and workplace, and corrosive to many materials. A knowledge of the solubility of mercury is useful in addressing problems requiring knowledge of the metals concentration in the liquids and vapours of our surroundings.


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 )

Density of Mercury

Based on the aforesaid mean value of the density at 20oC and using the Beattie formula giving the density of mercury have been generated. Apart from thermometry, mercury is used as a reference standard for determining the volume of small capacity measures and to maintain the primary standard barometer. In either case, the temperature range of interest is 0-41oC, so the density values have been calculated in steps of 0.1oC in this range. The value for the density of mercury refers to an ambient pressure of 101325 Pa. 

The density of mercury at 20 degree C to be 13545.848 kg/m3.

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.

Mercury Element Facts

  • Mercury is also a chemical element. Its common name is “quicksilver”. The element mercury is silver in colour. It can change very quickly.
  • Mercury is used in thermometers, mercury changes when the temperature changes. It expands or becomes larger at high temperatures. It contracts or becomes smaller at low temperatures.
  • One mercury gets into the body the body has a hard time getting rid of. Many rivers and streams are polluted with mercury.
  • Mercury is used in making lights and batteries. It is used in electrical switches. It is also in rat poisons and insecticides. It can also be used in medicine.

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.

Solved Example on Density of Mercury


A 20ml sample of mercury has a mass of 271g. Calculate the density of mercury.


Density = Mass/volume 

Density = 271g/20ml

Density of mercury element = 13.55 g/ml

This question tests the knowledge of a basic equation. Though the equation is simple one should be able to manipulate this equation so that one can connect this piece of information with other facts and formulas that are given in the passage.

Frequently Asked Questions – FAQs

Is Mercury dangerous to touch?

Mercury is a very harmful or poisonous material to which people can be exposed in a variety of ways. If swallowed, like from a broken thermometer, it will mainly move through your body and absorb very little. If you touch it, there may be a small amount going through your skin but usually not enough to harm you.

How is mercury found in nature?

In nature, mercury is rarely present as the pure, liquid metal, but rather in compounds and inorganic salts. Mercury is extracted as mercury (cinnabar ore) sulfide. Cinnabar deposits have been the source ores for the commercial exploitation of metallic mercury throughout history.

What is special about the Mercury element?

Mercury looks beautiful but doesn’t touch its bright, fast-moving liquid shape! It can be highly harmful to humans. The symbol Hg known for mercury comes from its Greek name, hydrargyrum, which means “liquid silver” — representing its shiny color. Mercury is a highly toxic constituent.

What mercury is used for?

Mercury can be used to produce thermometers, barometers, and other scientific tools. Mercury conducts electricity, and is used to make switches dependent on position and silence. Mercury vapor is used in streetlights, advertising signs and fluorescent lamps.

When was the element mercury discovered?

We have no idea who invented it. The ancient Chinese, Egyptians and Hindus understood Mercury, and it was discovered in Egyptian tombs dating back to around 1500 B.C. In the 4th Century B.C. We note Aristotle in writing referred to mercury as ‘hydro-argyros’ – which translates as liquid-silver or water-silver.

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