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Mercury

What is Mercury

Mercury (pronunciation: MER-kyoo-ree) is a heavy, silvery element belonging to the family of transition metals in the periodic table and represented by the chemical symbol Hg [1, 2, 3]. It is the only metal that exists in its liquid form at standard temperature and pressure conditions [4].

Mercury

Isotopes

Mercury is characterized by seven stable isotopes out of which 202Hg occurs most with a natural abundance of 29.86% [5]. There are about 34 radioactive isotopes of mercury with 194Hg and 203Hg being the longest-lived having half-life periods of 444 years and 46.612 days respectively [5].

Where is Mercury Found

It is mostly found combined with other elements in nature but can occur as tiny droplets in cinnabar, which are red mineral ores of mercury (II) sulfide [1]. The element is extracted by heating the mineral ore in the presence of air and then condensing the vapor [1]. China, Kyrgyzstan, and Chile are the top mercury-producing countries while Mexico, China, and Kyrgyzstan have the highest mercury reserves in the world [1].

History

Origin of its Name: It is named after ‘Mercury’, the fastest planet in the solar system to revolve around the Sun while its chemical symbol is derived from ‘hydrargyrum’, Greek for “liquid silver[2, 6]

Who discovered it: The element was probably discovered thousands of years ago and used by the ancient people in India, China, and Egypt, as it has been found in trace amounts in the 3500-year-old Egyptian tombs [2].

When and How was it Discovered

The early humans used cinnabar (mercury sulfide) to decorate the caves in France and Spain with paintings during the Paleolithic era about 30,000 years ago [1]. The metal was widely used by the ancient people as a liquid to extract gold from the sediment of rivers [1]. As a liquid, the mercury would dissolve gold that could be recovered through distillation of mercury [1].

The Spanish conquerors in the Americas obtained cinnabar from the mercury deposits at Huancavelica in Peru to extract gold [1]. It was also used by the miners to obtain gold from the New Almaden Mines during the California Gold Rush in 1848 [1]. Mercury was also used by several chemists, including Carl Wilhelm Scheele, Joseph Priestley, and Humphry Davy to discover other elements [7].

Mercury Symbol

Mercury Identification

Atomic number 80 [1]
CAS number 7439-97-6 [1]
Position in the periodic table Group Period Block
  12 [1] 6 [1] d [1]

Properties and Characteristics of Mercury

General Properties

Relative atomic mass 200.592 [1]
Atomic mass 200.592 amu [1]
Molar mass 200.5900 g/mol [8]
Molecular weight 200.592 g/mol [4]
Mass number 201 [9]

Physical Properties

Color Silvery-white [1, 7]
Melting point/freezing point -38.829 °C, -37.892 °F [1]
Boiling point 356.619 °C, 673.914 °F [1]
Density 13.5336 g cm-3 [1]
State of matter at room temperature (solid/liquid/gas) Liquid [1, 7]
Thermal (heat) conductivity 8.3 W/(m K) [10]
Specific heat 140 J kg-1 K-1 [1]
Bulk modulus 25 GPa [1]
Shear modulus Unknown [1]
Young’s modulus Unknown [1]
Vapor pressure
– Temperature (K) 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
– Pressure (Pa) 140

Chemical Properties

Oxidation states/oxidation number 2,1 [1]
Isotopes Isotope Mass Abundance (%) Half-life Mode of decay
  196Hg 195.966 0.15 > 2.5 X 1018 y α
  198Hg 197.967 9.97
  199Hg 198.968 16.87
  200Hg 199.968 23.1
  201Hg 200.970 13.18
  202Hg 201.971 29.86
  204Hg 203.973 6.87

Atomic Data of Mercury (Element 80)

Valence electrons 2 [1, 11]
Quantum numbers
– n 5 [12]
– ℓ 2 [12]
– m 2 [12]
– ms -1/2 [12]
Electron configuration (noble gas configuration) [Xe] 4f145d106s2 [1]
Atomic structure
– Number of electrons 80 [9]
– Number of neutrons 121 [9]
– Number of protons 80 [9]
Radius of Atom
– Atomic radius 2.23 Å [1]
– Covalent radius 1.32 Å [1]
Electronegativity (Pauling-scale) 1.9 [1]
Electron affinity Not stable [1]
Ionization energy (kJ mol-1) 1st 2nd 3rd 4th 5th 6th 7th 8th
  1007.066 1809.756 3299.8

Mercury Electron Configuration (Bohr Model)

What is It Used for

  • It is used in electrical switches and rectifiers because of its high electrical conductivity, and as catalysts in the chemical industry [1].
  • It easily forms alloys (or amalgams) with other metals like silver, tin, zinc, and gold [1, 2]. The amalgams were previously used for extracting gold from the ores and also for producing dental fillings [1, 2].
  • Mercuric sulfide, commonly called vermillion, is a bright-red pigment used for painting [1]. However, it is now cautiously used due to its high toxicity [1].
  • Mercury was commonly used in thermometers, barometers, batteries, fluorescent lights, and felt production [1, 7]. However, these have been discontinued [1].
  • Mercury compounds like HgCl2 (mercuric chloride) and Hg2Cl2 (mercurous chloride) were used for disinfecting wounds and kill bacteria as an antiseptic respectively [2].

Mercury Element 80

Its Toxicity and Health Effects

Mercury and its compounds are poisonous [1, 13]. Exposure through skin contact, inhalation, or ingestion usually affects the kidneys, stomach, intestines, and the nervous system [13].

It exists in every living organism in little amounts and enters the human body through the food we eat, with the daily intake being less than 0.01 mg [1]. However, consuming large amounts of mercury, especially methylmercury, can cause severe illness and death [1].

Mercury is not known to play any biological roles [1].

Interesting Facts

  • Alchemists thought that combining mercury with other metals would help in turning it into gold [6].
  • Mercury weighs 13-14 times more than the same volume of water [6].
  • The graphical representation of mercury is an alchemical symbol, also indicating the planet Mercury [1].

Mercury Lamp

Cost of Mercury

The price of pure mercury is $0.48 per gram, and in bulk, it costs $0.0174 per gram [7].

References

  1. http://www.rsc.org/periodic-table/element/80/mercury
  2. https://education.jlab.org/itselemental/ele080.html
  3. http://www.chemistryexplained.com/elements/L-P/Mercury.html
  4. https://pubchem.ncbi.nlm.nih.gov/compound/mercury#section=Top
  5. https://education.jlab.org/itselemental/iso080.html
  6. https://www.livescience.com/39232-facts-about-mercury.html
  7. https://www.chemicool.com/elements/mercury.html
  8. https://www.webqc.org/molecular-weight-of-Hg.html
  9. https://hobart.k12.in.us/ksms/PeriodicTable/mercury.htm
  10. http://periodictable.com/Elements/080/data.html
  11. https://environmentalchemistry.com/yogi/periodic/Hg.html
  12. http://chemistry-reference.com/q_elements.asp?Symbol=Hg
  13. https://emedicine.medscape.com/article/1175560-overview

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