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About Mercury

Mercury Bohr

Mercury is the only metal that is liquid at standard temperature and pressure, a property that results from a unique electron configuration that gives rise to unusually weak metallic bonds. Its chemical symbol Hg arises from the latin hydragyrum, meaning “liquid-silver”, and its common name was borrowed from the Roman god Mercury. The element was known to ancient civilizations, and though its metallic nature was not initially understood, its unique properties led it to be almost invariably seen as special or even imbued with magical powers. Its earliest uses were ceremonial, decorative, or medical; it was used in medical ointments and elixirs, cosmetics, and reflecting pools, and frequently was buried in large quantities alongside dead rulers. Medical uses of mercury are so embedded in some traditional healing practices that some practitioners still recommend the consumption of the mercury ore cinnabar for specific ailments or as a supplement for general health.

It has long been recognized that acute inhalations of mercury can lead to significant symptoms, but it is now understood that the slow elimination of most forms of mercury from the body ensures that even low levels can cause severe damage if chronic exposure allows for significant accumulation. A famous example of such gradual poisonings resulted from the use of mercuric nitrate in processing the animal skins used in 18th and 19th century hatmaking, which led to the coining of the phrase “mad as a hatter.” Increasing recognition of the dangers of chronic mercury exposure and of widespread environmental contamination due to mercury-containing products has driven significant reduction in many classical uses of the element.

Perhaps the most longstanding use of mercury not based primarily on its alluring physical properties was in amalgamation. Mercury will form amalgams with most common metals with the notable exception of iron; as early as 500 BCE this was exploited for extraction or refining of silver and gold. This practice continued in precious metal mining for centuries, though it’s use dwindled with increasing recognition of mercury’s toxicity until ceasing altogether in modern times. Amalgams were also widely used in dental fillings, and are still sometimes used this way today, though both toxicity and cosmetic concerns have led to their increasing replacement by alternative materials.

The pattern of widespread exploitation of unique properties followed by drastic scalebacks or total cessation of use in a given application due to greater recognition of safety risks has repeated throughout mercury’s history. Liquid mercury is opaque, dense, and displays almost-linear thermal expansion, making it ideal for use in instruments for measuring temperature or pressure. It is still used this way in some industrial and technical applications, but has been largely removed from medical equipment and most consumer versions of such products. Additionally, as a liquid that conducts electricity, it was used in mercury switches, which were often used in home light switches and thermostats, but these uses were discontinued. Mercury was also a common component of some types of batteries, but concerns about contaminations of landfills have all but eliminated this use. Mercury sulfide, which occurs naturally as the mineral cinnabar, has been used to produce brilliant warm-colored pigments, most famously “China red”, for centuries and is still used by some artists, but has been replaced by less-toxic pigments for most uses.

Even mercury’s toxicity has been exploited for practical applications. Mercury has been used in insecticides, herbicides, wood preservatives, and anti-fouling paints, but widespread use of all of these products have been discontinued. The organomercury preservative thiomersal was once used widely in vaccines, and though unlike most mercury compounds it produced a metabolite--ethylmercury--that was known to be eliminated from the body relatively quickly and therefore be nontoxic at the extremely low concentrations used in vaccines, public concern about the potential for toxicity has led to its elimination from most formulations. Mercury has also been used as an antiseptic and a diuretic, but these uses are now exceedingly rare and continue to decline.

Reductions in mercury usage in industrial applications have proceeded somewhat more slowly than the elimination of mercury from consumer products. Traditional chloralkali plants use mercury as one electrode in the electrolysis of sodium chloride to produce sodium hydroxide and chlorine gas. New chloralkali plants are required to be designed for use of alternative technology that does not require mercury, but existing plants still consume the majority of mercury produced. Mercury also continues to be used in a number of niche laboratory applications, including liquid mirror telescopes, and in the production of a few compound semiconductor materials used for infrared detection.

A notable exception to the elimination of mercury from consumer products is seen in the proliferation of fluorescent light bulbs which contain small amounts of mercury vapor. The energy efficiency of fluorescent bulbs compared to traditional incandescent lighting is generally considered to be an advantage large enough to outweigh the risks associated with the small amount of mercury the bulbs contain, however such bulbs do require careful disposal, and other energy efficient lighting technologies such as LEDs are beginning to be a competitive alternative for at least some lighting applications.

Mercury occurs naturally in elemental form on occasion, but is mostly found as the sulfide mineral cinnabar. It is extracted from this mineral by roasting to produce mercury vapor and sulfur dioxide. Mercury is also sometimes recovered as a byproduct of silver and gold mining, and recycling of old mercury-containing devices is a significant source of the metal.


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High Purity (99.999%) Mercury Oxide (HgO) Powder Mercury is used in the manufacture of industrial chemicals and in electronic applications. For example, mercury is used as gaseous mercury in fluorescent lamps. Some thermometers, particularly those which are used to measure high temperatures, still use mercury. Many of the applications that mercury has been used for in the past are slowly being phased out due to health and safety regulations. Mercury is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Mercury is available in elemental or metallic form as mercury liquid. Mercury oxides are available for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Mercury is also available in soluble forms including chlorides and nitrates. These compounds can be manufactured as solutions at specified stoichiometries.

Mercury Properties

Mercury Bohr ModelMercury is a Block D, Group 12, Period 6 element. The number of electrons in each of Mercury's shells is 2, 8, 18,32, 18, 2 and its electronic configuration is [Xe] 4f14 5d10 6s2. The mercury atom has a radius of and its Van der Waals radius is In its elemental form, CAS 7439-97-6, mercury has a silvery appearance. Mercury is found both as a native metal and in cinnabar, corderoite, and livingstonite ores. Mercury was named after the planet "Mercury" and has been known since ancient times.

Symbol: Hg
Atomic Number: 80
Atomic Weight: 200.59
Element Category: transition metal
Group, Period, Block: 12, 6, d
Color: silvery white/ silvery-white
Other Names: Mercure, Quecksilber, Mercurio
Melting Point: 38.83 °C, 37.89 °F, 234.32 K
Boiling Point: 356.73 °C, 674.11 °F, 629.88 K
Density: 13.534 g/cm3
Liquid Density @ Melting Point: N/A
Density @ 20°C: 13.546 g/cm3
Density of Solid: 14190 kg·m3
Specific Heat: 0.14 (kJ/kg K)
Superconductivity Temperature: 3.95 [or -269.2 °C (-452.6 °F)] K
Triple Point: 234.3156 K, 1.65×10 7 kPa
Critical Point: 1750 K, 172.00 MPa
Heat of Fusion (kJ·mol-1): 2.331
Heat of Vaporization (kJ·mol-1): 59.11
Heat of Atomization (kJ·mol-1): 64.463
Thermal Conductivity: 8.30 W·m-1·K-1
Thermal Expansion: (25 °C) 60.4 µm·m-1·K-1
Electrical Resistivity: (25 °C) 961nΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 27.983 J·mol-1·K-1
Young's Modulus: N/A
Shear Modulus: N/A
Bulk Modulus: N/A
Poisson Ratio: N/A
Mohs Hardness: N/A
Vickers Hardness: N/A
Brinell Hardness: N/A
Speed of Sound: (liquid, 20 °C) 1451.4 m·s-1
Pauling Electronegativity: 2
Sanderson Electronegativity: 2.2
Allred Rochow Electronegativity: 1.44
Mulliken-Jaffe Electronegativity: 1.81 (sp orbital)
Allen Electronegativity: N/A
Pauling Electropositivity: 2
Reflectivity (%): 73
Refractive Index: 1.000933  
Electrons: 80
Protons: 80
Neutrons: 121
Electron Configuration: [Xe] 4f14 5d10 6s2
Atomic Radius: 151 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 132±5 pm
Covalent Radius (Å): 1.32
Van der Waals Radius: 155 pm
Oxidation States: 4, 2 (mercuric), 1 (mercurous) (mildly basic oxide)
Phase: Liquid
Crystal Structure: rhombohedral
Magnetic Ordering: diamagnetic
Electron Affinity (kJ·mol-1) Not stable
1st Ionization Energy: 1007.07 kJ·mol-1
2nd Ionization Energy: 1809.69 kJ·mol-1
3rd Ionization Energy: 3299.82 kJ·mol-1
CAS Number: 7439-97-6
EC Number: 231-106-7
MDL Number: MFCD00011035
Beilstein Number: N/A
SMILES Identifier: [Hg]
InChI Identifier: InChI=1S/Hg
PubChem CID: 23931
ChemSpider ID: 22373
Earth - Total: 7.9 ppb
Mercury - Total: 0.09 ppb
Venus - Total: 8.3 ppb
Earth - Seawater (Oceans), ppb by weight: 0.05
Earth - Seawater (Oceans), ppb by atoms: 0.0015
Earth -  Crust (Crustal Rocks), ppb by weight: 67
Earth -  Crust (Crustal Rocks), ppb by atoms: 7
Sun - Total, ppb by weight: 20
Sun - Total, ppb by atoms: 0.12
Stream, ppb by weight: 0.07
Stream, ppb by atoms: 0.0004
Meterorite (Carbonaceous), ppb by weight: 250
Meterorite (Carbonaceous), ppb by atoms: 20
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 1
Universe, ppb by atom: 0.006
Discovered By: N/A
Discovery Date: Prior to 2000 BC
First Isolation: N/A

Health, Safety & Transportation Information for Mercury

Mercury is very toxic. Safety data for Mercury and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental (metallic) Mercury.

Safety Data
Material Safety Data Sheet MSDS
Signal Word Danger
Hazard Statements H330-H360D-H372-H410
Hazard Codes T+,N
Risk Codes 61-26-48/23-50/53
Safety Precautions 53-45-60-61
RTECS Number OV4550000
Transport Information UN 2809 8/PG 3
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Environment-Hazardous to the aquatic environment Health Hazard Skull and Crossbones-Acute Toxicity

Mercury Isotopes

Mercury has seven stable isotopes:

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
171Hg 171.00376(32)# 80(30) µs [59(+36-16) µs] Unknown 3/2-# N/A 1291.69 -
172Hg 171.99883(22) 420(240) µs [0.25(+35-9) ms] Unknown 0 N/A 1309.09 -
173Hg 172.99724(22)# 1.1(4) ms [0.6(+5-2) ms] Unknown 3/2-# N/A 1317.17 -
174Hg 173.992864(21) 2.0(4) ms [2.1(+18-7) ms] Unknown 0+ N/A 1325.25 -
175Hg 174.99142(11) 10.8(4) ms a to 171Pt 5/2-# N/A 1333.33 -
176Hg 175.987355(15) 20.4(15) ms a to 172Pt; ß+ to 176Au 0+ N/A 1350.72 -
177Hg 176.98628(8) 127.3(18) ms a to 173Pt; ß+ to 177Au 5/2-# N/A 1358.8 -
178Hg 177.982483(14) 0.269(3) s a to 174Pt; ß+ to 178Au 0+ N/A 1366.88 -
179Hg 178.981834(29) 1.09(4) s a to 175Pt; ß+ to 179Au; ß+ + p to 178Pt 5/2-# N/A 1374.96 -
180Hg 179.978266(15) 2.58(1) s ß+ to 180Au; a to 176Pt; SF 0+ N/A 1392.35 -
181Hg 180.977819(17) 3.6(1) s ß+ to 181Au; a to 177Pt; ß+ + p to 180Pt; ß+ + a to 177Ir 1/2(-) N/A 1400.43 -
182Hg 181.97469(1) 10.83(6) s ß+ to 182Au; a to 178Pt; ß+ + p to 181Pt 0+ N/A 1408.51 -
183Hg 182.974450(9) 9.4(7) s ß+ to 183Au; a to 179Pt; ß+ + p to 182Pt 1/2- N/A 1416.59 -
184Hg 183.971713(11) 30.6(3) s ß+ to 184Au; a to 180Pt 0+ N/A 1424.67 -
185Hg 184.971899(17) 49.1(10) s ß+ to 185Au; a to 181Pt 1/2- N/A 1432.74 -
186Hg 185.969362(12) 1.38(6) min ß+ to 186Au; a to 182Pt 0+ N/A 1450.14 -
187Hg 186.969814(15) 1.9(3) min ß+ to 187Au; a to 183Pt 3/2- N/A 1458.22 -
188Hg 187.967577(12) 3.25(15) min ß+ to 188Au; a to 184Pt 0+ N/A 1466.3 -
189Hg 188.96819(4) 7.6(1) min ß+ to 189Au; a to 185Pt 3/2- N/A 1474.38 -
190Hg 189.966322(17) 20.0(5) min ß+ to 190Au; a to 186Pt 0+ N/A 1482.45 -
191Hg 190.967157(24) 49(10) min ß+ to 191Au 3/2(-) N/A 1490.53 -
192Hg 191.965634(17) 4.85(20) h EC to 192Au; a to 188Pt 0+ N/A 1498.61 -
193Hg 192.966665(17) 3.80(15) h ß+ to 193Au 3/2- N/A 1506.69 -
194Hg 193.965439(13) 444(77) y EC to 194Au 0+ N/A 1514.77 -
195Hg 194.966720(25) 10.53(3) h EC to 195Au 1/2- 0.541475 1522.85 -
196Hg 195.965833(3) Observationally Stable - 0+ N/A 1530.93 0.15
197Hg 196.967213(3) 64.14(5) h EC to 197Au 1/2- 0.527374 1539.01 -
198Hg 197.9667690(4) Observationally Stable - 0+ N/A 1547.08 9.97
199Hg 198.9682799(4) Observationally Stable - 1/2- 0.5058852 1555.16 16.87
200Hg 199.9683260(4) Observationally Stable - 0+ N/A 1563.24 23.1
201Hg 200.9703023(6) Observationally Stable - 3/2- -0.560225 1562 13.18
202Hg 201.9706430(6) Observationally Stable - 0+ N/A 1570.08 29.86
203Hg 202.9728725(18) 46.595(6) d ß- to 203Tl 5/2- 0.8489 1578.16 -
204Hg 203.9734939(4) Observationally Stable - 0+ N/A 1586.24 6.87
205Hg 204.976073(4) 5.14(9) min ß- to 205Tl 1/2- N/A 1594.32 -
206Hg 205.977514(22) 8.15(10) min ß- to 206Tl 0+ N/A 1602.4 -
207Hg 206.98259(16) 2.9(2) min ß- to 207Tl (9/2+) N/A 1601.16 -
208Hg 207.98594(32)# 42(5) min [41(+5-4) min] ß- to 208Tl 0+ N/A 1609.24 -
209Hg 208.99104(21)# 37(8) s Unknown 9/2+# N/A 1608 -
210Hg 209.99451(32)# 10# min [>300 ns] Unknown 0+ N/A 1616.08 -