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Mercury, also called '''quicksilver''', is a Chemical Element in the Periodic Table that has the symbol '''Hg''' (from the Latinized Greek '''''hydrargyrum''''', for ''watery'' ''liquid'' ''silver'') and Atomic Number 80. A heavy, silvery, Transition Metal , mercury is one of five elements that are Liquid at or near standard room temperature (the others are the metals Caesium , Francium , and Gallium , and the Nonmetal Bromine ). Mercury is used in Dental Amalgam as well as Thermometer s, Barometer s and other scientific apparatus, although the use of mercury in thermometers has been largely phased out in clinical and scientific environments (in favor of Alcohol -filled, digital or Thermistor -based replacements) in the interests of health and safety due to the toxicity of the element. Mercury is mostly obtained by reduction from the Mineral Cinnabar . Its high Density allows things such as billiard balls to float with less than 20% of their volume submerged. Applications Mercury is used primarily for the manufacture of industrial chemicals or for electrical and electronic applications. It is used in some Thermometer s, especially ones which are used to measure high temperatures (In the United States, non-prescription sale of mercury fever thermometers was banned by a number of different states and localities). Other uses:
Miscellaneous uses: Mercury Switch es, Mercury Cell s for Sodium Hydroxide and Chlorine production, Electrode s in some types of Electrolysis , Batteries ( Mercury Cells ), and Catalyst s, Insecticide s, Dental Amalgam s/preparations and Liquid Mirror telescopes. Historical uses: preserving wood, developing Daguerreotype s, Silvering Mirror s, anti-fouling paints (discontinued in 1990), Herbicide s (discontinued in 1995), cleaning, and in-road leveling devices in cars. Mercury compounds have been used in Antiseptic s, Laxative s, Antidepressant s, and Antisyphilitics . It was also allegedly used by Allied Spies to sabotage German planes. A mercury paste was applied to bare Aluminium , causing the metal to rapidly Corrode . This would cause mysterious structural failures. In Islamic Spain it was used for filling decorative pools and for fountains [http://www.positiveatheism.org/hist/draper05.htm . In some applications, mercury can be replaced with less toxic but considerably more expensive Galinstan Alloy . History Mercury was known to the ancient Chinese and Hindu s and was found in Egypt ian tombs that date from 1500 BC. In China , India and Tibet , mercury use was thought to prolong life, heal fractures, and maintain generally good health. China's first emperor, Shi Huang Ti, is said to have been buried in a tomb that contained rivers of flowing mercury, representative of the rivers of China. The Ancient Greek s used mercury in ointments and the Romans used it in Cosmetics . By 500 BC mercury was used to make Amalgams with other metals. The Indian word for Alchemy is ''Rassayana'' which means ‘the way of mercury.’ Alchemists often thought of mercury as the first Matter from which all metals were formed. Different Metals could be produced by varying the quality and quantity of Sulfur contained within the mercury. An ability to transform mercury into any metal resulted from the essentially mercurial quality of all metals. The purest of these was Gold , and mercury was required for the Transmutation of base (or impure) metals into gold. This was a primary goal of alchemy, either for material or spiritual gain. Hg is the modern Chemical Symbol for mercury. It comes from ''hydrargyrum'', a Latin ized form of the Greek word ''`Υδραργυρος'' (''hydrargyros''), which is a compound word meaning 'water' and 'silver' — since it is liquid, like water, and yet has a silvery metallic sheen. 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 (above left). Mercury is the only metal for which the alchemical planetary name became the common name. From the mid-18th to the mid-19th centuries, a process called "carroting" was used in the making of Felt Hats . Animal skins were rinsed in an orange solution of the mercury compound Mercuric Nitrate , Hg(NO3)2·2H2O. This process separated the fur from the pelt and matted it together. This solution and the vapors it produced were highly toxic. Its use resulted in widespread cases of Mercury Poisoning among hatters. Symptoms included Tremor s, Emotional Lability , Insomnia , Dementia and Hallucination s. The United States Public Health Service banned the use of mercury in the felt industry in December 1941. The psychological symptoms associated with mercury poisoning may have inspired the phrase "mad as a hatter"; see the Hatter article on the origin of the phrase. Dentistry Elemental mercury is the main ingredient in reported that, "amalgam fillings release small amounts of mercury vapor," but in such a small amount that it, "has not been shown to cause any … adverse health effects." This position is not shared by all governments and there is an ongoing Dental Amalgam Controversy . Medicine Mercury has been used in the treatment of illnesses for centuries. (partly ethyl mercury) since the 1930s ( FDA report ). Mercury(II) chloride was a disinfectant for doctors, patients and instruments. Mercury in the form of Cinnabar remains an important component of Chinese , Tibetan , and Ayurvedic medicine. As problems may arise when these medicines are exported to countries that prohibit the use of mercury in medicines, in recent times, less toxic substitutes have been devised. Today, mercuric medicines and devices are generally considered hazardous. Neither are used to the extent they were in the past. medications, including topical antiseptics, stimulant laxatives, diaper rash ointment, eye drops and nose sprays. The FDA has "inadequate data to establish general recognition of the safety and effectiveness," of the mercury ingredients in these products ( Code of federal regulations ). In the European Union , RoHS legislation being introduced will ban mercury from certain products, and limit the amount of mercury in other products to less than 1000 Ppm (except for certain exemptions). Mineral occurrence Mercury is an extremely rare element in the earth's crust, having an average crustal abundance by mass of only 0.08 parts per million. However, because it does not blend Geochemically with those elements that comprise the majority of the crustal mass, mercury ores can be extraordinarily concentrated considering the element's abundance in ordinary rock. The richest mercury ores contain up to 2.5% mercury by mass, and even the leanest concentrated deposits are at least 0.1% mercury (12,000 times average crustal abundance). This makes mercury ore the most easily depleted of all metal ores. Depletion of mercury ores have been a major concern since the 1960s and it is now almost certain that the last mineable deposits were discovered in Algeria in the mid-1970s. Since the early 1970s, total world production of mercury has fallen from 9,000 Tonne s to 1,600 tonnes due to depletion of reserves. It is found either as a native metal (rare) or in Cinnabar , Corderoite , Livingstonite , and other Mineral s with cinnabar (Hg S ) being the most common ore. Most present-day production occurs in Spain , Kyrgyzstan , China and Tajikistan . Over 100,000 tons of mercury were mined from the region of Huancavelica , Peru , over the course of three centuries following the discovery of deposits there in 1563; mercury from Huancavelica was crucial in the production of silver in colonial Spanish America. Many former ores in Italy , Slovenia , the United States and Mexico which once produced a large proportion of the world's supply have now been completely mined out. The metal is extracted by heating cinnabar in a current of air and condensing the vapor. The equation for this extraction is :HgS + O2 → Hg + SO2 See also ''''. Compounds The most important salts are:
Laboratory tests have found that an electrical discharge causes the Noble Gases to combine with mercury vapor. These compounds are held together with Van Der Waals Force s and result in HgNe, HgAr, HgKr, and HgXe. Organic mercury Compound s are also important. Methylmercury is a dangerous compound that is widely found as a Pollutant in water bodies and streams. See also ''''. Isotopes There are seven stable Isotope s of mercury with Hg-202 being the most abundant (29.86%). The longest-lived Radioisotope s are Hg-194 with a Half-life of 444 years, and Hg-203 with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lifes that are less than a day. Occurrence in the environment Abundance
Preindustrial deposition rates of mercury from the atmosphere may be in the range of 4 ng/L in the western USA. Although that can be considered a natural level of exposure, regional or global sources have significant effects. Volcanic eruptions can increase the atmospheric source by 4–6 times. {Link without Title} Mercury enters the environment as a pollutant from various industries:
Mercury also enters into the environment through the disposal (e.g., landfilling, incineration) of certain products. Products containing mercury include: auto parts, efforts are cutting back or eliminating mercury in such products. For example, most Thermometer s now use pigmented Alcohol instead of mercury. Mercury thermometers are still occasionally used in the medical field because they are more accurate than alcohol thermometers, though both are being replaced by electronic thermometers. Mercury thermometers are still widely used for certain scientific applications because of their greater accuracy and working range. One of the worst Industrial Disasters in history was caused by the dumping of mercury compounds into Minamata Bay, Japan. The Chisso Corporation , a Fertilizer and later petrochemical company, was found responsible for polluting the bay from 1932–1968. It is estimated that over 3,000 people suffered various deformities, severe mercury poisoning symptoms or death from what became known as Minamata Disease . Health and Environmental Effects See Mercury Poisoning Precautions and regulation Mercury should be handled with care. Containers of mercury should be securely sealed to avoid spills and evaporation. Heating of mercury, or compounds of mercury that may decompose when heated, should always be carried out with adequate ventilation in order to avoid human exposure to mercury vapor. Occupational exposure Due to the health effects of mercury exposure, industrial and commercial uses are regulated in many countries. The World Health Organization , OSHA , and NIOSH all treat mercury as an occupational hazard, and have established specific occupational exposure limits. Environmental releases and disposal of mercury are regulated in the U.S. primarily by the Environmental Protection Agency . Mercury in fish Fish and Shellfish have a natural tendency to concentrate mercury in their bodies, often in the form of Methylmercury , a highly toxic organic compound of mercury. Species of fish that are high on the Food Chain , such as Shark , Swordfish , King Mackerel , Albacore Tuna , and Tilefish contain higher concentrations of mercury than others. This is because mercury is stored in the fat tissues of fish, and when a predatory fish eats another fish, it tends to retain the fat, while excreting other body parts. Thus species that are high on the Food Chain amass body burdens of mercury that can be ten times higher, or more, than the species they consume. This process is called Biomagnification . Because methylmercury and high levels of elemental mercury can be particularly toxic to unborn or young children, organizations such as the U.S. EPA and FDA recommend that women who are pregnant or plan to become pregnant within the next one or two years, as well as young children avoid eating these species in large amounts. Species with characteristically low levels of mercury include Shrimp , Tilapia , Salmon , Pollock , and Catfish (FDA March 2004). The FDA characterizes shrimp, catfish, pollock, salmon, and canned light tuna as low-mercury seafood, although recent tests have indicated that up to 6 percent of canned light tuna may contain high levels. ( Chicago Tribune ) Release of mercury into the environment The primary sources of mercury to the environment are Fossil Fuel burning (primarily Coal ) and solid waste Incineration (Nriagu & Pacyna, 1988). The United States rule was issued, with most of the reductions in mercury pollution from power plants beginning in the year 2018. The rule was being subjected to legal challenges filed by several States in 2005. Mercury and aluminium Mercury readily combines with Aluminium to form an amalgam when the two pure metals come into contact. However, when the amalgam is exposed to air, the aluminium oxidizes, leaving behind mercury. The oxide flakes away, exposing more mercury amalgam, which repeats the process. This process continues until the supply of amalgam is exhausted, and since it releases mercury, a small amount of mercury can “eat through” a large amount of aluminium over time, by progressively forming amalgam and relinquishing the aluminium as oxide. Aluminium in air is ordinarily protected by a molecule-thin layer of its own oxide (which is not porous to oxygen). Mercury coming into contact with this oxide does no harm. However, if any elemental aluminium is exposed (even by a recent scratch), the mercury may combine with it, starting the process described above, and potentially damaging a large part of the aluminium before it finally ends (Ornitz 1998). For this reason, restrictions are placed on the use and handling of mercury in proximity with aluminium. In particular, mercury is not allowed aboard aircraft under most circumstances because of the risk of it forming amalgam with exposed aluminium parts in the aircraft. References
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