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97-831: Located between mountains, it has a temperate climate, favourable for agriculture. The mountains have lead and zinc ore deposits. Chengxian is noted for its walnut production. Chengxian walnuts were designated a protected origin product in China in 2014. In January 2021, the Qingni River in Chengxian was found to be polluted with thallium from zinc production wastewater. Cheng County is divided to 14 towns and 3 townships. - Towns are upgraded from Township. -Former Townships are merged to other. Longnan Chengzhou Airport opened in 2018 and offers domestic flights. The Tianshui–Longnan railway started construction in 2020 and will be

194-400: A half-life of 444 years, and Hg with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day. Hg occurs naturally in tiny traces as an intermediate decay product of U . Hg and Hg are the most often studied NMR -active nuclei, having spins of 1 ⁄ 2 and 3 ⁄ 2 respectively. Hg is

291-442: A melting point of −38.83 °C and a boiling point of 356.73 °C, both the lowest of any stable metal, although preliminary experiments on copernicium and flerovium have indicated that they have even lower boiling points. This effect is due to lanthanide contraction and relativistic contraction reducing the orbit radius of the outermost electrons, and thus weakening the metallic bonding in mercury. Upon freezing,

388-434: A mercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth (as in iron rusting ), even small amounts of mercury can seriously corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in

485-425: A nuclear medicine scan, during one type of nuclear cardiac stress test . Soluble thallium salts (many of which are nearly tasteless) are highly toxic and they were historically used in rat poisons and insecticides . Because of their nonselective toxicity, use of these compounds has been restricted or banned in many countries. Thallium poisoning usually results in hair loss. Because of its historic popularity as

582-640: A soft metal , mercury forms very stable derivatives with the heavier chalcogens . Preeminent is mercury(II) sulfide , HgS, which occurs in nature as the ore cinnabar and is the brilliant pigment vermilion . Like ZnS , HgS crystallizes in two forms , the reddish cubic form and the black zinc blende form. The latter sometimes occurs naturally as metacinnabar . Mercury(II) selenide (HgSe) and mercury(II) telluride (HgTe) are known, these as well as various derivatives, e.g. mercury cadmium telluride and mercury zinc telluride being semiconductors useful as infrared detector materials. Mercury(II) salts form

679-463: A basic and soluble thallium source in organic and organometallic chemistry. Organothallium compounds tend to be thermally unstable, in concordance with the trend of decreasing thermal stability down group 13. The chemical reactivity of the Tl–C bond is also the lowest in the group, especially for ionic compounds of the type R 2 TlX. Thallium forms the stable [Tl(CH 3 ) 2 ] ion in aqueous solution; like

776-593: A chamber 60 feet below the 1800-year-old pyramid known as the Temple of the Feathered Serpent , the third-largest pyramid of Teotihuacan , Mexico, along with "jade statues, jaguar remains, a box filled with carved shells and rubber balls". In Lamanai , once a major city of the Maya civilization , a pool of mercury was found under a marker in a Mesoamerican ballcourt . Aristotle recounts that Daedalus made

873-459: A digital display. Some transit telescopes use a basin of mercury to form a flat and absolutely horizontal mirror, useful in determining an absolute vertical or perpendicular reference. Concave horizontal parabolic mirrors may be formed by rotating liquid mercury on a disk, the parabolic form of the liquid thus formed reflecting and focusing incident light. Such liquid-mirror telescopes are cheaper than conventional large mirror telescopes by up to

970-401: A factor of 100, but the mirror cannot be tilted and always points straight up. Liquid mercury is part of a popular secondary reference electrode (called the calomel electrode ) in electrochemistry as an alternative to the standard hydrogen electrode . The calomel electrode is used to work out the electrode potential of half cells . The triple point of mercury, −38.8344 °C, is

1067-671: A high index of refraction . Combined with sulfur or selenium and arsenic, thallium has been used in the production of high- density glasses that have low melting points in the range of 125 and 150 Celsius°. These glasses have room-temperature properties that are similar to ordinary glasses and are durable, insoluble in water and have unique refractive indices . Thallium(I) sulfide's electrical conductivity changes with exposure to infrared light , making this compound useful in photoresistors . Thallium selenide has been used in bolometers for infrared detection. Doping selenium semiconductors with thallium improves their performance, thus it

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1164-597: A large part of the work, especially the isolation of the metallic thallium was done by Lamy, Crookes tried to secure his own priority on the work. Lamy was awarded a medal at the International Exhibition in London 1862: For the discovery of a new and abundant source of thallium and after heavy protest Crookes also received a medal: thallium, for the discovery of the new element. The controversy between both scientists continued through 1862 and 1863. Most of

1261-487: 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. Mercury is an ingredient in dental amalgams . Thiomersal (called Thimerosal in the United States) is an organic compound used as a preservative in vaccines , although this use

1358-456: A murder weapon, thallium has gained notoriety as "the poisoner's poison" and "inheritance powder" (alongside arsenic ). A thallium atom has 81 electrons, arranged in the electron configuration [Xe]4f 5d 6s 6p ; of these, the three outermost electrons in the sixth shell are valence electrons. Due to the inert pair effect , the 6s electron pair is relativistically stabilised and it is more difficult to get these involved in chemical bonding than it

1455-448: A positive charge. One example is Hg 3 (AsF 6 ) 2 containing the Hg 3 cation. Mercury(II) is the most common oxidation state and is the main one in nature as well. All four mercuric halides are known and have been demonstrated to form linear coordination geometry , despite mercury's tendency to form tetrahedral molecular geometry with other ligands. This behavior

1552-632: A trace element in iron pyrite , and thallium is extracted as a by-product of roasting this mineral for the production of sulfuric acid . Thallium can also be obtained from the smelting of lead and zinc ores. Manganese nodules found on the ocean floor contain some thallium. In addition, several other thallium minerals, containing 16% to 60% thallium, occur in nature as complexes of sulfides or selenides that primarily contain antimony , arsenic , copper, lead, and silver . These minerals are rare, and have had no commercial importance as sources of thallium. The Allchar deposit in southern North Macedonia

1649-550: A transportable generator, which is similar to the technetium-99m generator . The generator contains lead-201 (half-life 9.33 hours), which decays by electron capture to thallium-201. The lead-201 can be produced in a cyclotron by the bombardment of thallium with protons or deuterons by the (p,3n) and (d,4n) reactions. A thallium stress test is a form of scintigraphy in which the amount of thallium in tissues correlates with tissue blood supply. Viable cardiac cells have normal Na /K ion-exchange pumps . The Tl cation binds

1746-459: A variety of complex derivatives with ammonia . These include Millon's base (Hg 2 N ), the one-dimensional polymer (salts of HgNH 2 ) n ), and "fusible white precipitate" or [Hg(NH 3 ) 2 ]Cl 2 . Known as Nessler's reagent , potassium tetraiodomercurate(II) ( K 2 HgI 4 ) is still occasionally used to test for ammonia owing to its tendency to form the deeply colored iodide salt of Millon's base. Mercury fulminate

1843-506: A wooden statue of Aphrodite move by pouring quicksilver in its interior. In Greek mythology Daedalus gave the appearance of voice in his statues using quicksilver. The ancient Greeks used cinnabar (mercury sulfide) in ointments; the ancient Egyptians and the Romans used it in cosmetics . By 500 BC mercury was used to make amalgams (Medieval Latin amalgama , "alloy of mercury") with other metals. Alchemists thought of mercury as

1940-474: Is a detonator widely used in explosives . Organic mercury compounds are historically important but are of little industrial value in the western world. Mercury(II) salts are a rare example of simple metal complexes that react directly with aromatic rings. Organomercury compounds are always divalent and usually two-coordinate and linear geometry. Unlike organocadmium and organozinc compounds, organomercury compounds do not react with water. They usually have

2037-437: Is a black solid which decomposes above 800 °C, forming the thallium(I) oxide and oxygen. The simplest possible thallium compound, thallane (TlH 3 ), is too unstable to exist in bulk, both due to the instability of the +3 oxidation state as well as poor overlap of the valence 6s and 6p orbitals of thallium with the 1s orbital of hydrogen. The trihalides are more stable, although they are chemically distinct from those of

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2134-400: Is a constituent of the alloy in the anode plates of magnesium seawater batteries . Soluble thallium salts are added to gold plating baths to increase the speed of plating and to reduce grain size within the gold layer. A saturated solution of equal parts of thallium(I) formate (Tl(HCO 2 )) and thallium(I) malonate (Tl(C 3 H 3 O 4 )) in water is known as Clerici solution . It

2231-411: Is a mobile, odorless liquid which changes from yellowish to colorless upon reducing the concentration of the thallium salts. With a density of 4.25 g/cm at 20 °C, Clerici solution is one of the heaviest aqueous solutions known. It was used in the 20th century for measuring the density of minerals by the flotation method, but its use has discontinued due to the high toxicity and corrosiveness of

2328-562: Is a topical antiseptic used for minor cuts and scrapes in some countries. Today, the use of mercury in medicine has greatly declined in all respects, especially in developed countries. Mercury is still used in some diuretics , although substitutes such as thiazides now exist for most therapeutic uses. In 2003, mercury compounds were found in some over-the-counter drugs , including topical antiseptics , stimulant laxatives, diaper-rash ointment , eye drops , and nasal sprays . The FDA has "inadequate data to establish general recognition of

2425-409: 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 is a heavy, silvery-white metal that is liquid at room temperature. Compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity. It has

2522-480: Is an exception, and iron flasks have traditionally been used to transport the material. Several other first row transition metals with the exception of manganese , copper and zinc are also resistant in forming amalgams. Other elements that do not readily form amalgams with mercury include platinum . Sodium amalgam is a common reducing agent in organic synthesis , and is also used in high-pressure sodium lamps. Mercury readily combines with aluminium to form

2619-545: Is dangerous, and adequate ventilation is necessary when melting this metal. Thallium(I) compounds have a high aqueous solubility and are readily absorbed through the skin, and care should be taken to avoid this route of exposure, as cutaneous absorption can exceed the absorbed dose received by inhalation at the permissible exposure limit (PEL). Exposure by inhalation cannot safely exceed 0.1 mg/m in an eight-hour time-weighted average (40-hour work week). The Centers for Disease Control and Prevention (CDC) states, "Thallium

2716-460: Is derived. 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 . Mercury occurs in deposits throughout the world mostly as cinnabar ( mercuric sulfide ). The red pigment vermilion

2813-420: Is either extracted from the dusts from the smelter flues or from residues such as slag that are collected at the end of the smelting process. The raw materials used for thallium production contain large amounts of other materials and therefore a purification is the first step. The thallium is leached either by the use of an alkali or sulfuric acid from the material. The thallium is precipitated several times from

2910-440: Is estimated to be 0.7 mg/kg, mostly in association with potassium -based minerals in clays , soils , and granites . The major source of thallium for practical purposes is the trace amount that is found in copper , lead , zinc , and other heavy-metal- sulfide ores . Thallium is found in the minerals crookesite TlCu 7 Se 4 , hutchinsonite TlPbAs 5 S 9 , and lorándite TlAsS 2 . Thallium also occurs as

3007-432: Is for the heavier elements. Thus, very few electrons are available for metallic bonding, similar to the neighboring elements mercury and lead . Thallium, then, like its congeners, is a soft, highly electrically conducting metal with a low melting point, of 304 °C. A number of standard electrode potentials, depending on the reaction under study, are reported for thallium, reflecting the greatly decreased stability of

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3104-449: Is formed. Sulfuric and nitric acids dissolve thallium rapidly to make the sulfate and nitrate salts, while hydrochloric acid forms an insoluble thallium(I) chloride layer. Thallium has 41 isotopes which have atomic masses that range from 176 to 216. Tl and Tl are the only stable isotopes and make up nearly all of natural thallium. The five short-lived isotopes Tl through Tl inclusive occur in nature, as they are part of

3201-432: Is in decline. Although it was widely speculated that this mercury-based preservative could cause or trigger autism in children, no evidence supports 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 the inactivated influenza vaccine. Merbromin (Mercurochrome), another mercury compound,

3298-459: Is not classifiable as a carcinogen, and it is not suspected to be a carcinogen. It is unknown whether chronic or repeated exposure to thallium increases the risk of reproductive toxicity or developmental toxicity. Chronic high level exposure to thallium through inhalation has been reported to cause nervous system effects, such as numbness of fingers and toes." For a long time thallium compounds were readily available as rat poison. This fact and that it

3395-426: Is obtained by grinding natural cinnabar or synthetic mercuric sulfide. Exposure to mercury and mercury-containing organic compounds is toxic to the nervous system , immune system and kidneys of humans and other animals; mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury ) either directly or through mechanisms of biomagnification . Mercury

3492-591: Is ongoing to develop high-temperature superconducting materials for such applications as magnetic resonance imaging , storage of magnetic energy, magnetic propulsion , and electric power generation and transmission. The research in applications started after the discovery of the first thallium barium calcium copper oxide superconductor in 1988. Thallium cuprate superconductors have been discovered that have transition temperatures above 120 K. Some mercury-doped thallium-cuprate superconductors have transition temperatures above 130 K at ambient pressure, nearly as high as

3589-409: Is produced not from potassium ores, but as a byproduct from refining of heavy-metal sulfide ores. Approximately 65% of thallium production is used in the electronics industry and the remainder is used in the pharmaceutical industry and in glass manufacturing . It is also used in infrared detectors . The radioisotope thallium-201 (as the soluble chloride TlCl) is used in small amounts as an agent in

3686-597: Is similar to the Ag ion. The best known mercury halide is mercury(II) chloride , an easily sublimating white solid. Mercury(II) oxide , the main oxide of mercury, arises when the metal is exposed to air for long periods at elevated temperatures. It reverts to the elements upon heating near 400 °C, as was demonstrated by Joseph Priestley in an early synthesis of pure oxygen . Hydroxides of mercury are poorly characterized, as attempted isolation studies of mercury(II) hydroxide have yielded mercury oxide instead. Being

3783-519: Is the most popular isotope used for thallium nuclear cardiac stress tests . Thallium(III) compounds resemble the corresponding aluminium(III) compounds. They are moderately strong oxidizing agents and are usually unstable, as illustrated by the positive reduction potential for the Tl /Tl couple. Some mixed-valence compounds are also known, such as Tl 4 O 3 and TlCl 2 , which contain both thallium(I) and thallium(III). Thallium(III) oxide , Tl 2 O 3 ,

3880-573: Is used as the ligand). Mercury(I) chloride , a colorless solid also known as calomel , is really the compound with the formula Hg 2 Cl 2 , with the connectivity Cl-Hg-Hg-Cl. It reacts with chlorine to give mercury(II) chloride , which resists further oxidation. Mercury(I) hydride , a colorless gas, has the formula HgH, containing no Hg-Hg bond; however, the gas has only ever been observed as isolated molecules. Indicative of its tendency to bond to itself, mercury forms mercury polycations , which consist of linear chains of mercury centers, capped with

3977-400: Is used in thermometers , barometers , manometers , sphygmomanometers , float valves , mercury switches , mercury relays , fluorescent lamps and other devices, although concerns about the element's toxicity have led to the phasing out of such mercury-containing instruments. It remains in use in scientific research applications and in amalgam for dental restoration in some locales. It

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4074-518: Is used in some liquid-in-glass thermometers , especially those used to measure high temperatures. A still increasing amount is used as gaseous mercury in fluorescent lamps , while most of the other applications are slowly being phased out due to health and safety regulations. In some applications, mercury is replaced with less toxic but considerably more expensive Galinstan alloy . Mercury and its compounds have been used in medicine, although they are much less common today than they once were, now that

4171-429: Is used in trace amounts in selenium rectifiers . Another application of thallium doping is the sodium iodide and cesium iodide crystals in gamma radiation detection devices. In these, the sodium iodide crystals are doped with a small amount of thallium to improve their efficiency as scintillation generators. Some of the electrodes in dissolved oxygen analyzers contain thallium. Research activity with thallium

4268-483: Is water-soluble and nearly tasteless led to frequent intoxication caused by accident or criminal intent. One of the main methods of removing thallium (both radioactive and stable) from humans is to use Prussian blue , a material which absorbs thallium. Up to 20 grams per day of Prussian blue is fed by mouth to the patient, and it passes through their digestive system and comes out in their stool. Hemodialysis and hemoperfusion are also used to remove thallium from

4365-591: 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. The mines in Almadén (Spain), Monte Amiata (Italy), and Idrija (now Slovenia) dominated mercury production from

4462-478: The Neolithic Age . 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 vapor leads to serious adverse health effects. The first emperor of a unified 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

4559-565: The international exhibition , which opened on 1 May that year. Thallium tends to form the +3 and +1 oxidation states. The +3 state resembles that of the other elements in group 13 ( boron , aluminium , gallium , indium ). However, the +1 state, which is far more prominent in thallium than the elements above it, recalls the chemistry of alkali metals and thallium(I) ions are found geologically mostly in potassium-based ores and (when ingested) are handled in many ways like potassium ions (K ) by ion pumps in living cells. Commercially, thallium

4656-552: The +3 oxidation state: Thallium is the first element in group 13 where the reduction of the +3 oxidation state to the +1 oxidation state is spontaneous under standard conditions. Since bond energies decrease down the group, with thallium, the energy released in forming two additional bonds and attaining the +3 state is not always enough to outweigh the energy needed to involve the 6s-electrons. Accordingly, thallium(I) oxide and hydroxide are more basic and thallium(III) oxide and hydroxide are more acidic, showing that thallium conforms to

4753-546: The 1650s. Fahrenheit's mercury thermometer was based on an earlier design that used alcohol rather than mercury; the mercury thermometer was significantly more accurate than those using alcohol. From the early 21st century onwards, the use of mercury thermometers has been declining, and mercury-containing instruments have been banned in many jurisdictions following the 1998 Protocol on Heavy Metals . Modern alternatives to mercury thermometers include resistance thermometers , thermocouples , and thermistor sensors that output to

4850-548: The 1960s onward, the majority of industrial plants moved away from mercury cell processes towards diaphragm cell technologies to produce chlorine, though 11% of the chlorine made in the United States was still produced with the mercury cell method as of 2005. Thermometers containing mercury were invented in the early 18th century by Daniel Gabriel Fahrenheit , though earlier attempts at making temperature-measuring instruments filled with quicksilver had been described in

4947-434: The K pumps and is transported into the cells. Exercise or dipyridamole induces widening ( vasodilation ) of arteries in the body. This produces coronary steal by areas where arteries are maximally dilated. Areas of infarct or ischemic tissue will remain "cold". Pre- and post-stress thallium may indicate areas that will benefit from myocardial revascularization . Redistribution indicates the existence of coronary steal and

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5044-399: The United States and Mexico, which once produced a large proportion of the world supply, have now been completely mined out or, in the case of Slovenia ( Idrija ) and Spain ( Almadén ), shut down due to the fall of the price of mercury. Nevada 's McDermitt Mine, the last mercury mine in the United States, closed in 1992. The price of mercury has been highly volatile over the years and in 2006

5141-405: The aircraft. Mercury embrittlement is the most common type of liquid metal embrittlement, as mercury is a natural component of some hydrocarbon reservoirs and will come into contact with petroleum processing equipment under normal conditions. There are seven stable isotopes of mercury, with Hg being the most abundant (29.86%). The longest-lived radioisotopes are Hg with

5238-503: The blood serum. At later stages of the treatment, additional potassium is used to mobilize thallium from the tissues. According to the United States Environmental Protection Agency (EPA), artificially-made sources of thallium pollution include gaseous emission of cement factories , coal-burning power plants, and metal sewers. The main source of elevated thallium concentrations in water is

5335-475: The composition of minerals and chemical products. Crookes and Lamy both started to use the new method. Crookes used it to make spectroscopic determinations for tellurium on selenium compounds deposited in the lead chamber of a sulfuric acid production plant near Tilkerode in the Harz mountains . He had obtained the samples for his research on selenium cyanide from August Hofmann years earlier. By 1862, Crookes

5432-464: 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). It is found either as a native metal (rare) or in cinnabar , metacinnabar , sphalerite , corderoite , livingstonite and other minerals , with cinnabar (HgS) being

5529-531: The dimeric cation, Hg 2 . Stable derivatives include the chloride and nitrate . In aqueous solution of a mercury(I) salt, slight disproportion of Hg 2 into Hg and Hg results in >0.5% of dissolved mercury existing as Hg . In these solutions, complexation of the Hg with addition of ligands such as cyanide causes disproportionation to go to completion, with all Hg 2 precipitating as elemental mercury and insoluble mercury(II) compounds (e.g. mercury(II) cyanide if cyanide

5626-626: The discussion ended after Crookes was elected Fellow of the Royal Society in June 1863. The dominant use of thallium was the use as poison for rodents. After several accidents the use as poison was banned in the United States by Presidential Executive Order 11643 in February 1972. In subsequent years several other countries also banned its use. Thallium concentration in the Earth's crust

5723-557: The first railway to serve the county. China National Highway 567 and G7011 Shiyan–Tianshui Expressway are the main roads connecting the county. Thallium Thallium is a chemical element ; it has symbol Tl and atomic number 81. It is a silvery-white post-transition metal that is not found free in nature. When isolated, thallium resembles tin , but discolors when exposed to air. Chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861, in residues of sulfuric acid production. Both used

5820-539: 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 that 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 effects from therapeutic doses are typically reversible. Although this form of mercury appears to be less toxic than other forms, its use in traditional Chinese medicine has not yet been justified, as

5917-471: The formula HgR 2 , which are often volatile, or HgRX, which are often solids, where R is aryl or alkyl and X is usually halide or acetate. Methylmercury , a generic term for compounds with the formula CH 3 HgX, is a dangerous family of compounds that are often found in polluted water. They arise by a process known as biomethylation . Mercury is used primarily for the manufacture of industrial chemicals or for electrical and electronic applications. It

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6014-439: The general rule of elements being more electropositive in their lower oxidation states. Thallium is malleable and sectile enough to be cut with a knife at room temperature. It has a metallic luster that, when exposed to air, quickly tarnishes to a bluish-gray tinge, resembling lead. It may be preserved by immersion in oil. A heavy layer of oxide builds up on thallium if left in air. In the presence of water, thallium hydroxide

6111-700: The historic Almaden Quicksilver Mine and created a county park on the site, after conducting extensive safety and environmental analysis of the property. All known mercury compounds exhibit one of two positive oxidation states: I and II. Experiments have failed to unequivocally demonstrate any higher oxidation states: both the claimed 1976 electrosynthesis of an unstable Hg(III) species and 2007 cryogenic isolation of HgF 4 have disputed interpretations and remain difficult (if not impossible) to reproduce. Unlike its lighter neighbors, cadmium and zinc, mercury usually forms simple stable compounds with metal-metal bonds. Most mercury(I) compounds are diamagnetic and feature

6208-521: The isoelectronic Hg(CH 3 ) 2 and [Pb(CH 3 ) 2 ] , it is linear. Trimethylthallium and triethylthallium are, like the corresponding gallium and indium compounds, flammable liquids with low melting points. Like indium, thallium cyclopentadienyl compounds contain thallium(I), in contrast to gallium(III). Thallium ( Greek θαλλός , thallos , meaning "a green shoot or twig") was discovered by William Crookes and Claude Auguste Lamy , working independently, both using flame spectroscopy (Crookes

6305-490: The largest use of mercury in the late 20th century was in the mercury cell process (also called the Castner-Kellner process ) where metallic sodium is formed as an amalgam at a cathode made from mercury; this sodium is then reacted with water to produce sodium hydroxide. Many of the industrial mercury releases of the 20th century came from this process, although modern plants claim to be safe in this regard. From

6402-476: The leaching of thallium from ore processing operations. Mercury (element) Mercury is a chemical element ; it has symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum ( / h aɪ ˈ d r ɑːr dʒ ər ə m / hy- DRAR -jər-əm ) from the Greek words hydor ' water ' and argyros ' silver ' , from which its chemical symbol

6499-424: The legal limit ( permissible exposure limit ) for thallium exposure in the workplace as 0.1 mg/m skin exposure over an eight-hour workday. The National Institute for Occupational Safety and Health (NIOSH) also set a recommended exposure limit (REL) of 0.1 mg/m skin exposure over an eight-hour workday. At levels of 15 mg/m , thallium is immediately dangerous to life and health . Contact with skin

6596-473: The lighter group 13 elements and are still the least stable in the whole group. For instance, thallium(III) fluoride , TlF 3 , has the β-BiF 3 structure rather than that of the lighter group 13 trifluorides, and does not form the TlF 4 complex anion in aqueous solution. The trichloride and tribromide disproportionate just above room temperature to give the monohalides, and thallium triiodide contains

6693-552: The linear triiodide anion ( I 3 ) and is actually a thallium(I) compound. Thallium(III) sesquichalcogenides do not exist. The thallium(I) halides are stable. In keeping with the large size of the Tl cation, the chloride and bromide have the caesium chloride structure, while the fluoride and iodide have distorted sodium chloride structures. Like the analogous silver compounds, TlCl, TlBr, and TlI are photosensitive and display poor solubility in water. The stability of thallium(I) compounds demonstrates its differences from

6790-542: The mercury for the colonies. Mercury deposits were discovered in the New World, and more than 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. The patio process and later pan amalgamation process continued to create great demand for mercury to treat silver ores until the late 19th century. Former mines in Italy,

6887-569: The mercury required for CFL bulb manufacture. Environmental dangers have been a concern, particularly in the southern cities of Foshan and Guangzhou , and in Guizhou province in the southwest. Abandoned mercury mine processing sites often contain very hazardous waste piles of roasted cinnabar calcines . Water run-off from such sites is a recognized source of ecological damage. Former mercury mines may be suited for constructive re-use; for example, in 1976 Santa Clara County, California purchased

6984-606: The mining of cinnabar and refining for mercury are hazardous and historic causes of mercury poisoning. In China, prison labor was used by a private mining company as recently as the 1950s to develop new cinnabar mines. Thousands of prisoners were used by the Luo Xi mining company to establish new tunnels. Worker health in functioning mines is at high risk. A newspaper claimed that an unidentified European Union directive calling for energy-efficient lightbulbs to be made mandatory by 2012 encouraged China to re-open cinnabar mines to obtain

7081-501: The modern chemical symbol for mercury. It is an abbreviation of hydrargyrum , a romanized form of the ancient Greek name for mercury, ὑδράργυρος ( hydrargyros ). Hydrargyros is a Greek compound word meaning ' water-silver ' , from ὑδρ - ( hydr -), the root of ὕδωρ ( hydor ) ' water ' , and ἄργυρος ( argyros ) ' silver ' . Like the English name quicksilver ( ' living-silver ' ), this name

7178-691: The most common ore. Mercury ores often occur in hot springs or other volcanic regions. Beginning in 1558, with the invention of the patio process to extract silver from ore using mercury, mercury became an essential resource in the economy of Spain and its American colonies. Mercury was used to extract silver from the lucrative mines in New Spain and Peru . Initially, the Spanish Crown's mines in Almadén in Southern Spain supplied all

7275-480: The natural decay chains of heavier elements. Tl is the most stable radioisotope , with a half-life of 3.78 years. It is made by the neutron activation of stable thallium in a nuclear reactor . The most useful radioisotope, Tl (half-life 73 hours), decays by electron capture, emitting X-rays (~70–80 keV), and photons of 135 and 167 keV in 10% total abundance; therefore, it has good imaging characteristics without an excessive patient-radiation dose. It

7372-408: The newly developed method of flame spectroscopy , in which thallium produces a notable green spectral line. Thallium, from Greek θαλλός , thallós , meaning "green shoot" or "twig", was named by Crookes. It was isolated by both Lamy and Crookes in 1862; Lamy by electrolysis and Crookes by precipitation and melting of the resultant powder. Crookes exhibited it as a powder precipitated by zinc at

7469-409: The opening of the mine in Almadén 2500 years ago, until new deposits were found at the end of the 19th century. Mercury is an extremely rare element in Earth's crust ; it has an average crustal abundance by mass of only 0.08 parts per million (ppm) and is the 66th most abundant element in the Earth's crust. Because it does not blend geochemically with those elements that constitute the majority of

7566-468: The planet became one of the alchemical symbols for the metal, and Mercury became an alternative name for the metal. Mercury is the only metal for which the alchemical planetary name survives, as it was decided it was preferable to quicksilver as a chemical name. Mercury was found in Egyptian tombs that date from 1500 BC; cinnabar , the most common natural source of mercury, has been in use since

7663-486: The presence of ischemic coronary artery disease . A mercury–thallium alloy, which forms a eutectic at 8.5% thallium, is reported to freeze at −60 °C, some 20 °C below the freezing point of mercury. This alloy is used in thermometers and low-temperature switches. In organic synthesis, thallium(III) salts, as thallium trinitrate or triacetate, are useful reagents for performing different transformations in aromatics, ketones and olefins, among others. Thallium

7760-424: The production if a new application, such as a thallium-containing high-temperature superconductor , becomes practical for widespread use outside of the laboratory. The odorless and tasteless thallium sulfate was once widely used as rat poison and ant killer. Since 1972 this use has been prohibited in the United States due to safety concerns. Many other countries followed this example. Thallium salts were used in

7857-456: The rest of the group: a stable oxide , hydroxide , and carbonate are known, as are many chalcogenides. The double salt Tl 4 (OH) 2 CO 3 has been shown to have hydroxyl-centred triangles of thallium, [Tl 3 (OH)] , as a recurring motif throughout its solid structure. The metalorganic compound thallium ethoxide (TlOEt, TlOC 2 H 5 ) is a heavy liquid (ρ 3.49 g·cm , m.p. −3 °C), often used as

7954-483: The rivers of China—was reportedly killed by drinking a mercury and powdered jade mixture formulated by Qin alchemists intended as an elixir of immortality. Khumarawayh ibn Ahmad ibn Tulun , the second Tulunid ruler of Egypt (r. 884–896), known for his extravagance and profligacy , reportedly built a basin filled with mercury, on which he would lie on top of air-filled cushions and be rocked to sleep. In November 2014 "large quantities" of mercury were discovered in

8051-423: The safety and effectiveness" of the mercury ingredients in these products. Chlorine is produced from sodium chloride (common salt, NaCl) using electrolysis to separate metallic sodium from chlorine gas. Usually salt is dissolved in water to produce a brine. By-products of any such chloralkali process are hydrogen (H 2 ) and sodium hydroxide (NaOH), which is commonly called caustic soda or lye . By far

8148-436: The solution to remove impurities. At the end it is converted to thallium sulfate and the thallium is extracted by electrolysis on platinum or stainless steel plates. The production of thallium decreased by about 33% in the period from 1995 to 2009 – from about 15 metric tonnes to about 10 tonnes. Since there are several small deposits or ores with relatively high thallium content, it would be possible to increase

8245-489: The solution. Thallium iodide is frequently used as an additive in metal-halide lamps , often together with one or two halides of other metals. It allows optimization of the lamp temperature and color rendering, and shifts the spectral output to the green region, which is useful for underwater lighting. Thallium and its compounds are extremely toxic, with numerous recorded cases of fatal thallium poisoning. The Occupational Safety and Health Administration (OSHA) has set

8342-409: 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

8439-418: The therapeutic basis for the use of cinnabar is not clear. 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

8536-415: The toxic effects of mercury and its compounds are more widely understood. An example of the early therapeutic application of mercury was published in 1787 by James Lind . The first edition of The Merck Manuals (1899) featured many then-medically relevant mercuric compounds, such as mercury-ammonium chloride , yellow mercury proto-iodide , calomel , and mercuric chloride , among others. Mercury in

8633-602: The treatment of ringworm , other skin infections and to reduce the night sweating of tuberculosis patients. This use has been limited due to their narrow therapeutic index , and the development of improved medicines for these conditions. Thallium(I) bromide and thallium(I) iodide crystals have been used as infrared optical materials, because they are harder than other common infrared optics, and because they have transmission at significantly longer wavelengths. The trade name KRS-5 refers to this material. Thallium(I) oxide has been used to manufacture glasses that have

8730-941: The volume of mercury decreases by 3.59% and its density changes from 13.69 g/cm when liquid to 14.184 g/cm when solid. The coefficient of volume expansion is 181.59 × 10 at 0 °C, 181.71 × 10 at 20 °C and 182.50 × 10 at 100 °C (per °C). Solid mercury is malleable and ductile, and can be cut with a knife. Table of thermal and physical properties of liquid mercury: Mercury does not react with most acids, such as dilute sulfuric acid , although oxidizing acids such as concentrated sulfuric acid and nitric acid or aqua regia dissolve it to give sulfate , nitrate , and chloride . Like silver, mercury reacts with atmospheric hydrogen sulfide . Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury (spill kits also use activated carbon and powdered zinc). Mercury dissolves many metals such as gold and silver to form amalgams . Iron

8827-411: The world-record-holding mercury cuprates. Before the widespread application of technetium-99m in nuclear medicine , the radioactive isotope thallium-201 , with a half-life of 73 hours, was the main substance for nuclear cardiography . The nuclide is still used for stress tests for risk stratification in patients with coronary artery disease (CAD). This isotope of thallium can be generated using

8924-400: Was $ 650 per 76-pound (34.46 kg) flask . Mercury is extracted by heating cinnabar in a current of air and condensing the vapor. The equation for this extraction is: In 2020, China was the top producer of mercury, providing 88% of the world output (2200 out of 2500 tonnes), followed by Tajikistan (178 t), Russia (50 t) and Mexico (32 t). Because of the high toxicity of mercury, both

9021-399: Was able to isolate small quantities of the new element and determine the properties of a few compounds. Claude-Auguste Lamy used a spectrometer that was similar to Crookes' to determine the composition of a selenium-containing substance which was deposited during the production of sulfuric acid from pyrite . He also noticed the new green line in the spectra and concluded that a new element

9118-500: Was due to mercury's liquid and shiny properties. The modern English name mercury comes from the planet Mercury . In medieval alchemy , the seven known metals—quicksilver, gold , silver , copper , iron , lead , and tin —were associated with the seven planets. Quicksilver was associated with the fastest planet, which had been named after the Roman god Mercury , who was associated with speed and mobility. The astrological symbol for

9215-428: Was first to publish his findings, on March 30, 1861). The name comes from thallium's bright green spectral emission lines derived from the Greek 'thallos', meaning a green twig. After the publication of the improved method of flame spectroscopy by Robert Bunsen and Gustav Kirchhoff and the discovery of caesium and rubidium in the years 1859 to 1860, flame spectroscopy became an approved method to determine

9312-561: Was present. Lamy had received this material from the sulfuric acid plant of his friend Frédéric Kuhlmann and this by-product was available in large quantities. Lamy started to isolate the new element from that source. The fact that Lamy was able to work ample quantities of thallium enabled him to determine the properties of several compounds and in addition he prepared a small ingot of metallic thallium which he prepared by remelting thallium he had obtained by electrolysis of thallium salts. As both scientists discovered thallium independently and

9409-408: Was the only area where thallium was actively mined. This deposit still contains an estimated 500 tonnes of thallium, and it is a source for several rare thallium minerals, for example lorándite. The United States Geological Survey (USGS) estimates that the annual worldwide production of thallium is 10 metric tonnes as a by-product from the smelting of copper, zinc, and lead ores. Thallium

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