Figure 1. Mercury, atomic number of 80 and atomic weight of 200.592.[1]

Mercury (Hg) is the 80th element on the periodic table, is classified as a metal, and is liquid at room temperature. Its existence has been known for thousands of years, having been found in 3500 year old Egyptian tombs.[2]

Some useful properties of mercury include:[3]

Atomic weight 200.592
Density (at 0oC) 13.5336 g/cm3
Boiling point 629.769 K
Melting point 234.321 K
Embodied energy[4] 90-180 MJ/kg

Mercury is a toxic element which can enter the body through open wounds, inhalation, or ingestion. It accumulates in the body and can be harmful to internal organs and possibly cause death. It is not typically found free in nature, at least not in harmful enough levels to harm humans. Mercury is a pollutant that is released by humans in a variety of ways however, with humans contributing anywhere from 50-90% of the mercury present in the environment.[5][6]

To read more about mercury as a pollutant and its effects on the environment, visit Mercury (pollutant).

Uses of Mercury

Figure 2. A mercury switch on millimetre graph paper. The switch turns on when its body is tilted such that the mercury falls under gravity and touches the contacts, completing the circuit.[7]

Mercury is used in many scientific instruments such as thermometers and barometers.[2] Due to its electrical conductivity it is used to make silent switches, while its vapor form makes it useful in streetlights and fluorescent lamps.[2] Many of these uses are being phased out however, due to the aforementioned toxic properties of mercury.

Mercury forms alloys with other metals such as gold, silver, zinc and cadmium, known as amalgums. Amalgums are useful in extracting gold from ores, in dental fillings with silver, and extending the lifetime of zinc and cadmium batteries.[2]

The most common use currently is as a catalyst in chemical industries.[3]


The video below is from the University of Nottingham's periodic videos project.[8] They have created a complete suite of short videos on every element on the periodic table of elements.


  1. Made internally be a member of the Energy Education team, with information from Royal Society of Chemistry, Available:
  2. 2.0 2.1 2.2 2.3 Jefferson Labs. (Accessed May 14, 2016). The Element Mercury [Online], Available:
  3. 3.0 3.1 Royal Society of Chemistry. (Accessed May 14, 2016). Mercury [Online], Available:
  4. UNEP. (August 19, 2015). Environmental Risks and Challenges of Anthropogenic Metals Flows and Cycles [Online]. Available:
  5. United Nations Environment Programme. 2013. Global Mercury Assessment [Online] (Accessed July 22, 2015). Available:
  6. G. Tyler Miller, Jr. and D. Hackett, "What is the threat from Mercury?," in Living in the Environment, 2nd ed. USA: Nelson , 2011, ch.24, sec.8, pp.589-590
  7. Wikimedia Commons [Online], Available:
  8. See more videos from the University of Nottingham on different elements here: