Mercury is a chemical element with the symbol Hg (Hydrargyrum in Latin) and atomic number 80. It is a heavy, silvery metal that is liquid at room temperature and atmospheric pressure and when ingested, is poisonous. This metal is banned by the RoHS directive 2011.
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum (// hy-DRAR-jər-əm) from the Greek words hydro (water) and argyros (silver). A heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature.
|Appearance||shiny, silvery liquid|
|Standard atomic weight Ar°(Hg)|
|Mercury in the periodic table|
|Atomic number (Z)||80|
|Electron configuration||[Xe] 4f14 5d10 6s2|
|Electrons per shell||2, 8, 18, 32, 18, 2|
|Phase at STP||liquid|
|Melting point||234.3210 K (−38.8290 °C, −37.8922 °F)|
|Boiling point||629.88 K (356.73 °C, 674.11 °F)|
|Density (near r.t.)||13.546 g/cm3|
|Triple point||234.3156 K, 1.65×10−7 kPa|
|Critical point||1750 K, 172.00 MPa|
|Heat of fusion||2.29 kJ/mol|
|Heat of vaporization||59.11 kJ/mol|
|Molar heat capacity||27.983 J/(mol·K)|
|Oxidation states||−2 , +1, +2 (a mildly basic oxide)|
|Electronegativity||Pauling scale: 2.00|
|Atomic radius||empirical: 151 pm|
|Covalent radius||132±5 pm|
|Van der Waals radius||155 pm|
|Spectral lines of mercury|
|Speed of sound||liquid: 1451.4 m/s (at 20 °C)|
|Thermal expansion||60.4 µm/(m⋅K) (at 25 °C)|
|Thermal conductivity||8.30 W/(m⋅K)|
|Electrical resistivity||961 nΩ⋅m (at 25 °C)|
|Molar magnetic susceptibility||−33.44×10−6 cm3/mol (293 K)|
|Discovery||Ancient Egyptians (before 1500 BCE)|
|Symbol||"Hg": from its Latin name hydrargyrum, itself from Greek hydrárgyros, 'water-silver'|
|Isotopes of mercury|
Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alternatives such as alcohol- or galinstan-filled glass thermometers and thermistor- or infrared-based electronic instruments. Likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers. The mercury cell process (chlor-alkali) is used to produce chlorine and sodium or potassium hydroxide, but is phased out.
Mercury, and mercury compounds, remain in use in scientific research applications and in amalgam for dental restoration in some locales, and in some food manufacturing operations. In food manufacturing, mercuric chloride is used in the starch extraction process during rice, corn, and wheat refining to inhibit starch degrading enzymes. It is also used in fluorescent lighting. Electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light, which then causes the phosphor in the tube to fluoresce, making visible light.
Mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury), by inhalation of mercury vapor, or by ingesting any form of mercury. In serious form, it is also known as Minamata disease. Mercury poisoning is intensified with lead co-exposures.