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.
|Appearance||shiny, silvery liquid|
|Standard atomic weight Ar, std(Hg)||200.592(3)|
|Mercury in the periodic table|
|Atomic number (Z)||80|
|Element category||Post-transition metal, alternatively considered a transition metal|
|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.)||13.534 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 (mercurous), +2 (mercuric) (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|
|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)|
|Magnetic susceptibility||−33.44·10−6 cm3/mol (293 K)|
|Discovery||Ancient Egyptians (before 1500 BCE)|
|Main isotopes of mercury|
Mercury is a chemical element with the symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum (// hy-DRAR-jər-əm). A heavy, silvery d-block element, mercury is the only metallic element that is liquid at standard conditions for 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.
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.
Mercury remains in use in scientific research applications and in amalgam for dental restoration in some locales. 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.