Mercury (Hg)


  • Symbol: Hg
  • Atomic Number: 80
  • Atomic Weight: 200.592
  • Element Classification: Transition Metal
  • Discovered By: Known to ancient civilizations
  • Discovery Date: Used by ancient Egyptians and Sumerians by 1500 BC
  • Name Origin: Named after the Roman god Mercury; the symbol Hg comes from the element’s Greek name, hydrargyrum, meaning “liquid silver”
  • Density(g/cc): 13.5336
  • Melting Point: -38.83°C
  • Boiling Point: 356.73°C
  • Appearance: Silvery, liquid metal at room temperature
  • Atomic Radius(pm): 150


Mercury has been known since ancient times, with its use documented among the ancient Egyptians, Sumerians, and Chinese. The element was used for various purposes, including in cosmetics, medicines, and alchemical practices. The Greeks referred to mercury as hydrargyrum, from which the symbol Hg is derived, meaning “liquid silver” due to its shiny, fluid appearance. Mercury was named after the Roman messenger god Mercury, known for his speed and mobility, a reference to the metal’s liquid state at room temperature.

Relation to Other Elements

Mercury is a transition metal, unique among metals for being liquid at room temperature. It is part of group 12 in the periodic table, alongside zinc and cadmium, sharing some chemical properties such as forming +2 oxidation state compounds. However, mercury’s liquid state and high density set it apart from other metals. It has a closed-shell electron configuration, which contributes to its low chemical reactivity compared to many other metals.

Natural Occurrence

Mercury is found in the Earth’s crust primarily in the form of the ore cinnabar (mercury sulfide, HgS), from which it is extracted through heating and condensation. The largest mercury deposits are found in Spain, Italy, and Slovenia, but mercury is also produced in China, Kyrgyzstan, and other countries. The use of mercury has decreased due to environmental concerns and its toxicity.


Despite its toxicity, mercury has several applications, although many are being phased out for safer alternatives:

  • Amalgams: Mercury is used in dental amalgams for filling cavities, though its use has declined in favor of less toxic materials.
  • Measuring Devices: Traditionally, mercury was used in thermometers, barometers, and sphygmomanometers because of its expansive thermal range and uniform thermal expansion. Many of these uses have been replaced by digital devices.
  • Mining: Mercury has been used in the extraction of gold and silver from ore through amalgamation, a process that is now limited due to environmental concerns.
  • Electrical and Lighting: Mercury vapor is used in fluorescent lamps and some types of street lighting, although alternatives are increasingly being adopted.
  • Chemical Manufacturing: Mercury compounds are used as catalysts in the production of some chemicals and in batteries.

The historical use of mercury has had a significant impact on science, medicine, and industry. However, due to its toxicity and environmental impact, the use of mercury is being reduced, and safer alternatives are being developed and implemented across various applications.

Gold (Au)

Thallium (Tl)