Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum ( < Greek "hydr-" water and "argyros" silver). A heavy, silvery d-block element, mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature. With a freezing point of −38.83 °C and boiling point of 356.73 °C, mercury has one of the narrowest ranges of its liquid state of any metal.I
Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is mostly obtained by reduction from cinnabar. Cinnabar is highly toxic by ingestion or inhalation of the dust. Mercury poisoning can also result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury), inhalation of mercury vapor, or eating seafood contaminated with mercury.
Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, 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 alcohol-filled, galinstan-filled, digital, or thermistor-based instruments. It remains in use in scientific research applications and in amalgam material for dental restoration. It is used in lighting: electricity passed through mercury vapor in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light.
In China and Tibet, mercury use was thought to prolong life, heal fractures, and maintain generally good health, although it is now known that exposure to mercury leads to serious adverse health effects. The first emperor of China, Qín Shǐ Huáng Dì — allegedly buried in a tomb that contained rivers of flowing mercury on a model of the land he ruled, representative of the rivers of China — was killed by drinking a mercury and powdered jade mixture formulated by Qin alchemists (causing liver failure, mercury poisoning, and brain death) who intended to give him eternal life.
The ancient Greeks used mercury in ointments; the ancient Egyptians and the Romans used it in cosmetics which sometimes deformed the face. In Lamanai, once a major city of the Maya civilization, a pool of mercury was found under a marker in a Mesoamerican ballcourt. By 500 BC mercury was used to make amalgams (Medieval Latin amalgama, "alloy of mercury") with other metals.
Alchemists thought of mercury as the First Matter from which all metals were formed. They believed that different metals could be produced by varying the quality and quantity of sulfur contained within the mercury. The purest of these was gold, and mercury was called for in attempts at the transmutation of base (or impure) metals into gold, which was the goal of many alchemists.
Hg is the modern chemical symbol for mercury. It comes from hydrargyrum, a Latinized form of the Greek word Ύδραργυρος (hydrargyros), which is a compound word meaning "water-silver" (hydr- = water, argyros = silver) — since it is liquid like water and shiny like silver. The element was named after the Roman god Mercury, known for speed and mobility. It is associated with the planet Mercury; the astrological symbol for the planet is also one of the alchemical symbols for the metal; the Sanskrit word for alchemy is Rasavātam which means "the way of mercury". Mercury is the only metal for which the alchemical planetary name became the common name.
The mines in Almadén (Spain), Monte Amiata (Italy), and Idrija (now Slovenia) dominated mercury production from the opening of the mine in Almadén 2500 years ago, until new deposits were found at the end of the 19th century.
Mercury and its compounds have been used in medicine, although they are much less common today than they once were, now that the toxic effects of mercury and its compounds are more widely understood. The element mercury is an ingredient in dental amalgams. Thiomersal (called Thimerosal in the United States) is an organic compound used as a preservative in vaccines, though this use is in decline. Another mercury compound Merbromin (Mercurochrome) is a topical antiseptic used for minor cuts and scrapes is still in use in some countries.
Since the 1930s some vaccines have contained the preservative thiomersal, which is metabolized or degraded to ethyl mercury. Although it was widely speculated that this mercury-based preservative can cause or trigger autism in children, scientific studies showed no evidence supporting any such link. Nevertheless thiomersal has been removed from or reduced to trace amounts in all U.S. vaccines recommended for children 6 years of age and under, with the exception of inactivated influenza vaccine.
Mercury in the form of one of its common ores, cinnabar, is used in various traditional medicines, especially in traditional Chinese medicine. Review of its safety has found cinnabar can lead to significant mercury intoxication when heated, consumed in overdose or taken long term, and can have adverse effects at therapeutic doses, though this is typically reversible at therapeutic doses. Although this form of mercury appears less toxic than others, its use in traditional Chinese medicine has not yet been justified as the therapeutic basis for the use of cinnabar is not clear.
Historic medicinal uses
Mercury(I) chloride (also known as calomel or mercurous chloride) has been used in traditional medicine as a diuretic, topical disinfectant, and laxative. Mercury(II) chloride (also known as mercuric chloride or corrosive sublimate) was once used to treat syphilis (along with other mercury compounds), although it is so toxic that sometimes the symptoms of its toxicity were confused with those of the syphilis it was believed to treat. It is also used as a disinfectant. Blue mass, a pill or syrup in which mercury is the main ingredient, was prescribed throughout the 19th century for numerous conditions including constipation, depression, child-bearing and toothaches. In the early 20th century, mercury was administered to children yearly as a laxative and dewormer, and it was used in teething powders for infants. The mercury-containing organohalide merbromin (sometimes sold as Mercurochrome) is still widely used but has been banned in some countries such as the U.S.
- ↑ Senese, F. "Why is mercury a liquid at STP?". General Chemistry Online at Frostburg State University. http://antoine.frostburg.edu/chem/senese/101/inorganic/faq/why-is-mercury-liquid.shtml. Retrieved May 1, 2007.
- ↑ Norrby, L.J. (1991). "Why is mercury liquid? Or, why do relativistic effects not get into chemistry textbooks?". Journal of Chemical Education 68 (2): 110. doi:10.1021/ed068p110. Bibcode: 1991JChEd..68..110N.
- ↑ Template:RubberBible86th
- ↑ "Mercury and the environment — Basic facts". Environment Canada, Federal Government of Canada. 2004. http://www.ec.gc.ca/MERCURY/EN/bf.cfm. Retrieved 2008-03-27.
- ↑ "Mercury — Element of the ancients". Center for Environmental Health Sciences, Dartmouth College. http://www.dartmouth.edu/~toxmetal/toxic-metals/mercury/mercury-history.html. Retrieved 2012-04-09.
- ↑ "Qin Shihuang". Ministry of Culture, People's Republic of China. 2003. http://www.chinaculture.org/gb/en_aboutchina/2003-09/24/content_22854.htm. Retrieved 2008-03-27.
- ↑ Wright, David Curtis (2001). The History of China. Greenwood Publishing Group. p. 49. ISBN 0-313-30940-X.
- ↑ Pendergast, David M. (August 6, 1982). "Ancient maya mercury". Science 217 (4559): 533–535. doi:10.1126/science.217.4559.533. PMID 17820542. Bibcode: 1982Sci...217..533P.
- ↑ "Lamanai". http://www.guidetobelize.info/en/maya/belize-mayan-lamanai-guide.shtml. Retrieved June 17, 2011.
- ↑ Hesse R W (2007). Jewelrymaking through history. Greenwood Publishing Group. p. 120. ISBN 0-313-33507-9. http://books.google.com/?id=DIWEi5Hg93gC&pg=PA120.
- ↑ 11.0 11.1 Stillman, J. M. (2003). Story of Alchemy and Early Chemistry. Kessinger Publishing. pp. 7–9. ISBN 978-0-7661-3230-6. http://books.google.com/?id=hdaAGF5Y1N0C.
- ↑ Cox, R (1997). The Pillar of Celestial Fire. 1st World Publishing. p. 260. ISBN 1-887472-30-4. http://books.google.com/?id=ykEN2zHvCpQC&pg=PA260.
- ↑ Eisler, R. (2006). Mercury hazards to living organisms. CRC Press. ISBN 978-0-8493-9212-2. http://books.google.com/?id=gqc8wUvsI8cC&pg.
- ↑ FDA. "Thimerosal in Vaccines". http://www.fda.gov/Cber/vaccine/thimerosal.htm. Retrieved October 25, 2006.
- ↑ Parker SK, Schwartz B, Todd J, Pickering LK (2004). "Thimerosal-containing vaccines and autistic spectrum disorder: a critical review of published original data". Pediatrics 114 (3): 793–804. doi:10.1542/peds.2004-0434. PMID 15342856. Erratum (2005). Pediatrics 115 (1): 200. Template:DOI PMID 15630018.
- ↑ "Thimerosal in vaccines". Center for Biologics Evaluation and Research, U.S. Food and Drug Administration. 2007-09-06. http://www.fda.gov/cber/vaccine/thimerosal.htm. Retrieved 2007-10-01.
- ↑ Liu J, Shi JZ, Yu LM, Goyer RA, Waalkes MP (July 2008). "Mercury in traditional medicines: is cinnabar toxicologically similar to common mercurials?". Exp. Biol. Med. (Maywood) 233 (7): 810–7. doi:10.3181/0712-MR-336. PMID 18445765.
- ↑ Pimple, K.D. Pedroni, J.A. Berdon, V. (July 9, 2002). "Syphilis in history". Poynter Center for the Study of Ethics and American Institutions at Indiana University-Bloomington. http://www.indiana.edu/~poynter/sas/lb/syphilis.html. Retrieved April 17, 2005.
- ↑ Mayell, H. (2007-07-17). "Did Mercury in "Little Blue Pills" Make Abraham Lincoln Erratic?". National Geographic News. http://news.nationalgeographic.com/news/2001/07/0717_lincoln.html. Retrieved 2008-06-15.
- ↑ "What happened to Mercurochrome?". July 23, 2004. http://www.straightdope.com/columns/read/2518/what-happened-to-mercurochrome. Retrieved 2009-07-07.
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