Atomic Mass Of Mercury

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››More information on molar mass and molecular weight. In chemistry, the formula weight is a quantity computed by multiplying the atomic weight (in atomic mass units) of each element in a chemical formula by the number of atoms of that element present in the formula, then adding all of these products together. The atomic mass is useful in chemistry when it is paired with the mole concept: the atomic mass of an element, measured in amu, is the same as the mass in grams of one mole of an element. Thus, since the atomic mass of iron is 55.847 amu, one mole of iron atoms would weigh 55.847 grams.

  1. Atomic Mass of Mercury Atomic mass of Mercury is 200.59 u. Note that, each element may contain more isotopes, therefore this resulting atomic mass is calculated from naturally-occuring isotopes and their abundance. The unit of measure for mass is the atomic mass unit (amu).
  2. Example Exercise 9.1 Atomic Mass and Avogadro’s Number. The atomic mass of each element is listed below the symbol of the element in the periodic table: Cu = 63.55 amu, Hg = 200.59 amu, S = 32.07 amu, and He = 4.00 amu. The mass of Avogadro’s number of atoms is the atomic mass expressed in grams. Therefore, 6.02.
  3. In 1961, the Commission recommended Ar (Hg) = 200.59 (3) based on the chemical determinations. Published measurements of the isotopic composition of mercury agree remarkably well, giving Ar (Hg) values in the range 200.58 to 200.60.

Molar mass of HgH2 = 202.60588 g/mol

Convert grams Mercury(II) Hydride to moles or moles Mercury(II) Hydride to grams

Molecular weight calculation:
200.59 + 1.00794*2

Symbol# of AtomsMercuryHg200.59199.005%


In chemistry, the formula weight is a quantity computed by multiplying the atomic weight (in atomic mass units) of each element in a chemical formula by the number of atoms of that element present in the formula, then adding all of these products together.

Finding molar mass starts with units of grams per mole (g/mol). When calculating molecular weight of a chemical compound, it tells us how many grams are in one mole of that substance. The formula weight is simply the weight in atomic mass units of all the atoms in a given formula.

Using the chemical formula of the compound and the periodic table of elements, we can add up the atomic weights and calculate molecular weight of the substance.

Formula weights are especially useful in determining the relative weights of reagents and products in a chemical reaction. These relative weights computed from the chemical equation are sometimes called equation weights.

The atomic weights used on this site come from NIST, the National Institute of Standards and Technology. We use the most common isotopes. This is how to calculate molar mass (average molecular weight), which is based on isotropically weighted averages. This is not the same as molecular mass, which is the mass of a single molecule of well-defined isotopes. For bulk stoichiometric calculations, we are usually determining molar mass, which may also be called standard atomic weight or average atomic mass.

A common request on this site is to convert grams to moles. To complete this calculation, you have to know what substance you are trying to convert. The reason is that the molar mass of the substance affects the conversion. This site explains how to find molar mass.

If the formula used in calculating molar mass is the molecular formula, the formula weight computed is the molecular weight. The percentage by weight of any atom or group of atoms in a compound can be computed by dividing the total weight of the atom (or group of atoms) in the formula by the formula weight and multiplying by 100.

Mercury is a chemical element with symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum

Discovery and History

Mercury can be rightly considered as one of the elements with most ancient existence, and its discovery dates back to around 1500 B.C [1]. Initially, it was referred to as the water-silver or the liquid -silver (originated from the Greek term hydro-argyros used by Aristotle) and later Romans changed its name to Hydragyrum. In the 6th century, alchemists changed its name after the fast-moving Roman god, Mercury, with the symbol Hg (from its initial name Hydro-argyros). Mercury was greatly popular, especially in Chinese traditional medicine, due to its unique solid-liquid nature [2]. The metallic properties of mercury were discovered by Adam Braun and Mikhail Lomonosov (1759), who successfully froze a mercury thermometer.

Atomic Weight Of Mercury


Periodic Table ClassificationGroup 12
Period 6
State at 20CLiquid
Electron Configuration[Xe] 4f14 5d10 6s2
Electron Number80
Proton Number80
Electron Shell2, 8, 18, 32, 18, 2
Density13.55 at 20°C
Atomic number80
Atomic Mass200.59 g.mol -1
Electronegativity according to Pauling2.00


The occurrence of mercury is not very common. It is present in crust of the Earth on an average of 0.08 gram, making 0.003 ounce per ton of the rock. Mercury is rarely present in free, pure form and its principally present in the form of the red sulfide, termed as cinnabar (HgS). Naturally, mercury is present near hot springs and volcanoes in isolated drops or in larger fluid masses. Eruption of volcanoes can lead to 4-6 times increase in the atmospheric presence of volcanoes [3]. Around 2/3rd of supply of mercury in the world comes from China, and Chile and Kyrgyzstan make up the rest [4]. Mercury is often obtained as a by-product during the process of gold mining. Some other natural alloys of mercury have also been found, including potarite (with palladium) gold amalgam and moschellandsbergite (with silver), but these are extremely rare.

Physical characteristics

Atomic Mass Of Mercury Rounded Up

Mercury is a silver-white dense metal with a mirror like appearance. And have the unique characteristic of being liquid at room temperature. Mercury have boiling and melting points of 356.9 C and -38.87, respectively. It has atomic number of 80 and a molecular weight of 200.59 and belong to the Group 12 (Zinc group, II b) of the periodic table [2].

Chemical characteristics

Mercury is highly poisonous. It is generally stable in dry environment but exposure to water lead to the production of gray oxide coating on its surface. It has a low solubility for gases as compared to water. Mercury can vaporize and can stay in the atmosphere for many months.

Salts of Mercury

Various salts of mercury are present that have distinct characteristics and significances. These include mercury (I) chloride (used in medicine), Mercury (II) chloride (a very corrosive and poisonous substance);); Mercury (II) oxide (main oxide of mercury); Mercury fulminate (a detonator used in explosives widely; Mercury (II) selenide; Mercury (II) sulfide (found naturally as the ore cinnabar which is widely used paint pigment); Mercury (II) telluride, and Mercury zinc telluride (used in semiconductors) [2].

Significance and Uses

Despites its toxicity, mercury have found wide usage in variety of industries. Some of the main uses of mercury are described below:

  • Good electrical conductivity [5]

Used in making electrical switches

  • Low thermal conductivity with high thermal neutron capture [5]

Used as shield and coolant in nuclear reactors

  • Health care and dentistry [5]

Main use in production of dental amalgam, B.P apparatus (sphygmomanometers), and thermometers.

  • Agricultural industries

Used in making fungicides

  • Electricity generation

Due to higher boiling point as compared to water, vapors of mercury are being used instead of steam in electrical generating plants.

  • Cosmetic industry

Making mascaras

  • Mercury is used in mercury-vapor lamps (which emit light with UV radiation), and are used in street lights, UV lights and sun lamps.
  • Mercury is used the production of caustic soda (sodium hydroxide) and chlorine.

Health hazards

Toxicity of mercury is primarily caused by inhalation of the vapors, followed by ingestion of soluble compounds, or dermal absorption of mercury. Once released into the air, mercury gets widely dispersed and remain accumulated in the environment. Ultimately, it finds it way to the bottom of water bodies, and is transformed into methyl mercury, which is the more toxic organic form. Traces of methyl mercury contamination have been reported in fish tissues [6].

Isotopes of Mercury

There are 34 isotopes of mercury (mass number from 175-208). In natural form, mercury is a mixture of seven stable isotopes: 196Hg (0.15 percent), 198Hg (9.97 percent), 199Hg (16.87 percent), 200Hg (23.10 percent), 201Hg (13.18 percent), 202Hg (29.86 percent), and 204Hg (6.87 percent).


[1] Mary Elvira Weeks, The discovery of the elements. II. Elements known to the alchemists., J. Chem. Educ., 1932, 9 (1), p11

[2]. Rustagi, N., & Singh, R. (2010). Mercury and health care. Indian Journal of Occupational and Environmental Medicine, 14(2), 45–48.

[3]. Glacial Ice Cores Reveal A Record of Natural and Anthropogenic Atmospheric Mercury Deposition for the Last 270 Years. United States Geological Survey (USGS) Science for a changing world.

[4]. Brown TJ, Hetherington LE, Hannis SD, Bide T, Benham AJ, Idoine NE, et al. 1st ed. Keyworth, Nottigham: Natural Environment Research Council; 2009. World Mineral Production 2003-07.British Geological Survey

[5] Hammond CR. 81st ed. Cleveland, Ohio: CRC press; 2000. Elements, in Handbook of Chemistry and Physics. Available from: [last accessed on 2010 Apr 8] [Ref list]

[6] National Research Council. Toxicological effects of methylmercury. U.S: National Academies Press; 2000. Board on Environmental Studies and Toxicology. [Ref list]

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