Arsenic 897 225572589 2008-07-14T11:00:25Z CarsracBot 6929011 robot Modifying: [[uk:Миш'як]] {{Elementbox_header | number=33 | symbol=As | name=arsenic | left=[[germanium]] | right=[[selenium]] | above=[[phosphorus|P]] | below=[[antimony|Sb]] | color1=#cccc99 | color2=black }} {{Elementbox_series | [[metalloid]]s }} {{Elementbox_groupperiodblock | group=15 | period=4 | block=p }} {{Elementbox_appearance_img | As,33| metallic grey }} {{Elementbox_atomicmass_gpm | [[1 E-25 kg|74.92160]][[List of elements by atomic mass|(2)]] }} {{Elementbox_econfig | &#91;[[argon|Ar]]&#93; 4s<sup>2</sup> 3d<sup>10</sup> 4p<sup>3</sup> }} {{Elementbox_epershell | 2, 8, 18, 5 }} {{Elementbox_section_physicalprop | color1=#cccc99 | color2=black }} {{Elementbox_phase | [[solid]] }} {{Elementbox_density_gpcm3nrt | 5.727 }} {{Elementbox_densityliq_gpcm3mp | 5.22 }} {{Elementbox_meltingpoint | k=1090 | c=817 | f=1503 }} {{Elementbox_boilingpoint | k=[[sublimation (physics)|subl.]] 887 | c=614 | f=1137 }} |- | [[Critical temperature]] || 1673 [[kelvin|K]] {{Elementbox_heatfusion_kjpmol | (grey) 24.44 }} {{Elementbox_heatvaporiz_kjpmol | ? 34.76 }} {{Elementbox_heatcapacity_jpmolkat25 | 24.64 }} {{Elementbox_vaporpressure_katpa | 553 | 596 | 646 | 706 | 781 | 874 | comment= }} {{Elementbox_section_atomicprop | color1=#cccc99 | color2=black }} {{Elementbox_crystalstruct | rhombohedral }} {{Elementbox_oxistates | 5, '''3''', 1,<ref>{{cite web|url=http://pubs.acs.org/cgi-bin/abstract.cgi/inocaj/2004/43/i19/abs/ic049281s.html|title=Stabilized Arsenic(I) Iodide: A Ready Source of Arsenic Iodide Fragments and a Useful Reagent for the Generation of Clusters|accessdate=2007-12-10|publisher=ACS Publications}}</ref> -3<br />(mildly [[acid]]ic oxide) }} {{Elementbox_electroneg_pauling | 2.18 }} {{Elementbox_ionizationenergies4 | 947.0 | 1798 | 2735 }} {{Elementbox_atomicradius_pm | [[1 E-10 m|115]] }} {{Elementbox_atomicradiuscalc_pm | [[1 E-10 m|114]] }} {{Elementbox_covalentradius_pm | [[1 E-10 m|119]] }} {{Elementbox_vanderwaalsrad_pm | [[1 E-10 m|185]] }} {{Elementbox_section_miscellaneous | color1=#cccc99 | color2=black }} {{Elementbox_magnetic | no data }} {{Elementbox_eresist_ohmmat20 | 333 n}} {{Elementbox_thermalcond_wpmkat300k | 50.2 }} {{Elementbox_youngsmodulus_gpa | 8 }} {{Elementbox_bulkmodulus_gpa | 22 }} {{Elementbox_mohshardness | 3.5 }} {{Elementbox_brinellhardness_mpa | 1440 }} {{Elementbox_cas_number | 7440-38-2 }} {{Elementbox_isotopes_begin | color1=#cccc99 | color2=black }} {{Elementbox_isotopes_decay2 | mn=73 | sym=As | na=[[synthetic radioisotope|syn]] | hl=[[1 E6 s|80.3]] [[day|d]] | dm1=[[electron capture|ε]] | de1=- | pn1=73 | ps1=[[germanium|Ge]] | dm2=[[Gamma radiation|γ]] | de2=0.05[[Delayed nuclear radiation|D]], 0.01D, [[Conversion electron|e]] | pn2= | ps2=- }} {{Elementbox_isotopes_decay4 | mn=74 | sym=As | na=[[synthetic radioisotope|syn]] | hl=[[1 E6 s|17.78]] d | dm1=ε | de1=- | pn1=74 | ps1=[[germanium|Ge]] | dm2=[[Positron emission|β<sup>+</sup>]] | de2=0.941 | pn2=74 | ps2=[[germanium|Ge]] | dm3=γ | de3=0.595, 0.634 | pn3= | ps3=- | dm4=[[beta decay|β<sup>-</sup>]] | de4=1.35, 0.717 | pn4=74 | ps4=[[selenium|Se]] }} {{Elementbox_isotopes_stable | mn=75 | sym=As | na=100% | n=42 }} {{Elementbox_isotopes_end}} {{Elementbox_footer | color1=#cccc99 | color2=black }} '''Arsenic''' ({{pronEng|ˈɑrs<sup>ə</sup>n<s>ɪ</s>k}}) is a [[chemical element]] that has the symbol '''As''' and [[atomic number]] 33. Arsenic was first written about by [[Albertus Magnus]] ([[Germany]]) in 1250<ref name="BuildingBlocks451-3">{{cite book |last=Emsley |first=John |title=Nature's Building Blocks: An A-Z Guide to the Elements |year=2001 |id=ISBN 0-19-850341-5 |pages=43,513,529 |publisher=[[Oxford University Press]] |location=Oxford}}</ref>. Its Atomic Mass is 74.92. Its position in the [[periodic table]] is shown at right. This is a notoriously poisonous [[metalloid]] that has many [[allotropy|allotropic]] forms: yellow (molecular non-metallic) and several black and grey forms (metalloids) are a few that are seen. Three metalloidal forms of arsenic with different crystal structures are found free in nature (the minerals arsenic ''[[sensu stricto]]'' and the much rarer arsenolamprite and pararsenolamprite), but it is more commonly found as arsenide and arsenate compounds. Several hundred such mineral species are known. Arsenic and its compounds are used as [[pesticides]], [[herbicide]]s, [[insecticide]]s and various [[alloy]]s. The most common [[oxidation state]]s for arsenic are -3 (arsenides: usually alloy-like intermetallic compounds), +3 (arsenates(III) or arsenites, and most organoarsenic compounds), and +5 (arsenates(V): the most stable inorganic arsenic oxycompounds). Arsenic also bonds readily to itself, forming, for instance, As-As pairs in the red sulfide [[realgar]] and square As<sub>4</sub><sup>3-</sup> ions in the arsenide skutterudite. In the +3 oxidation state, the stereochemistry of arsenic is affected by possession of a [[lone pair]] of [[electrons]]. ==Notable characteristics== Arsenic is very similar chemically to its predecessor, [[phosphorus]]. Like phosphorus, it forms colourless, odourless, crystalline oxides [[Arsenic trioxide|As<sub>2</sub>O<sub>3</sub> ]] and [[Arsenic pentoxide|As<sub>2</sub>O<sub>5</sub>]] which are [[hygroscopic]] and readily soluble in water to form acidic solutions. [[Arsenic acid|Arsenic (V) acid]], like phosphorous acid, is a weak acid. Like phosphorus, arsenic forms an unstable, gaseous hydride: [[arsine]] (AsH<sub>3</sub>). The similarity is so great that arsenic will partly substitute for phosphorus in biochemical reactions and is thus [[arsenic poisoning|poison]]ous. However, in subtoxic doses, soluble arsenic compounds act as [[stimulant]]s, and were once popular in small doses as medicinals by people in the mid 18th century. When heated in air it [[oxidation|oxidizes]] to [[arsenic trioxide]]; the fumes from this reaction have an odor resembling [[garlic]]. This odor can be detected on striking arsenide minerals such as [[arsenopyrite]] with a hammer. Arsenic (and some arsenic compounds) [[sublimation (chemistry)|sublimes]] upon heating at atmospheric pressure, converting directly to a gaseous form without an intervening liquid state. The liquid state appears at 20 atmospheres and above, which explains why the melting point is higher than the boiling point <ref>[|http://www.corrosionsource.com/handbook/periodic/33.htm]</ref>. Elemental arsenic is found in many solid forms: the yellow form is soft, waxy and unstable, and is made of tetrahedral As<sub>4</sub> molecules similar to the molecules of white phosphorus. The grey, black or 'metallic' forms have somewhat layered crystal structures with bonds extending throughout the crystal. They are brittle [[semiconductors]] with a metallic luster. The [[density]] of the yellow form is 1.97 g/cm³; rhombohedral "grey arsenic" is much denser with a density of 5.73 g/cm³; the other metalloidal forms are similarly dense. ==Applications== [[Lead hydrogen arsenate]] was used well into the 20th century as an [[insecticide]] on [[fruit tree]]s. Its use sometimes resulted in [[brain damage]] to those working the sprayers. In the last half century, [[monosodium methyl arsenate]] (MSMA), a less toxic organic form of arsenic, has replaced lead arsenate's role in agriculture. [[Scheele's Green]], a copper arsenate, was used in the 19th century as a [[food dye|coloring agent]] in [[sweets]]. The application of most concern to the general public is probably that of [[wood]] treated with [[chromated copper arsenate]], also known as CCA or [[Tanalith]]. The vast majority of older [[lumber#Preservatives|pressure-treated]] wood was treated with CCA. CCA lumber is still in widespread use in many countries, and was heavily used during the latter half of the 20th century as a structural and outdoor [[building material]]. It was commonly used in situations where [[rot]] or [[insect]] infestation was a possibility. Although the use of CCA lumber was banned in many areas after studies showed that arsenic could leach out of the wood into the surrounding [[soil]] (from playground equipment, for instance), a risk is also presented by the burning of older CCA timber. The direct or indirect ingestion of wood ash from burnt CCA lumber has caused fatalities in animals and serious poisonings in humans; the lethal human dose is approximately 20 grams of ash. Scrap CCA lumber from construction and demolition sites may be inadvertently used in commercial and domestic fires. Protocols for safe disposal of CCA lumber do not exist evenly throughout the world; there is also concern in some quarters about the widespread [[landfill]] disposal of such timber. During the 18th, 19th, and 20th centuries, a number of arsenic compounds have been used as medicines, including [[arsphenamine]] (by [[Paul Ehrlich]]) and [[arsenic trioxide]] (by [[Thomas Fowler]]). Arsphenamine as well as [[Neosalvarsan]] was indicated for [[syphilis]] and [[trypanosomiasis]], but has been superseded by modern [[antibiotics]]. Arsenic trioxide has been used in a variety of ways over the past 200 years, but most commonly in the treatment of [[cancer]]. The US [[Food and Drug Administration]] in 2000 approved this compound for the treatment of patients with [[acute promyelocytic leukemia]] that is resistant to [[all-trans retinoic acid|ATRA]].<ref>Antman, Karen H. (2001). [http://theoncologist.alphamedpress.org/cgi/content/full/6/suppl_2/1 The History of Arsenic Trioxide in Cancer Therapy]. Introduction to a supplement to ''The Oncologist''. '''6''' (Suppl 2), 1-2. PMID 11331433.</ref> It was also used as [[Thomas Fowler|Fowler]]'s solution in [[psoriasis]].<ref>Huet ''et.al''. Noncirrhotic presinusoidal portal hypertension associated with chronic arsenical intoxication. ''Gastroenterology'' 1975;'''68'''(5 Pt 1):1270-7. PMID 1126603 </ref> Copper acetoarsenite was used as a green [[pigment]] known under many different names, including '[[Paris Green]]' and 'Emerald Green'. It caused numerous [[arsenic poisoning]]s. Other uses; * Various [[agriculture|agricultural]] insecticides, termination and poisons. * Used in animal feed, particularly in the US as a method of disease prevention and growth stimulation.{{Fact|date=May 2008}} * [[Gallium arsenide]] is an important [[semiconductor]] material, used in [[integrated circuit]]s. Circuits made using the compound are much faster (but also much more expensive) than those made in [[silicon]]. Unlike silicon it is [[direct bandgap]], and so can be used in [[laser diode]]s and [[LED]]s to directly convert [[electricity]] into [[light]]. * Also used in [[bronzing]] and [[pyrotechny]]. Recently new research has been done in locating tumours using arsenic-74 (a positron emitter). The advantages of using this isotope instead of the previously used [[iodine]]-124 is that the signal in the [[Positron emission tomography|PET scan]] is clearer as the iodine tends to transport iodine to the thyroid gland producing a lot of noise.<ref>''Journal of Clinical Cancer'' - 2008,14,1377 (DOI:10.1158/1078-0432.CCR-07-1516)</ref> ==History== The word ''arsenic'' is borrowed from the [[Persian language|Persian]] word زرنيخ ''Zarnikh'' meaning "yellow [[orpiment]]". ''Zarnikh'' was borrowed by [[Greek language|Greek]] as ''arsenikon'', which means masculine or potent. Arsenic has been known and used in [[Iran|Persia]] and elsewhere since ancient times. As the symptoms of [[arsenic poisoning]] were somewhat ill-defined, it was frequently used for [[murder]] until the advent of the [[Marsh test]], a sensitive chemical test for its presence. (Another less sensitive but more general test is the [[Reinsch test]].) Due to its use by the ruling class to murder one another and its potency and discreetness, arsenic has been called the ''Poison of Kings'' and the ''King of Poisons''. During the [[Bronze Age]], arsenic was often included in [[bronze]], which made the alloy harder (so-called "[[arsenical bronze]]"). Arsenic was first isolated by [[Geber]] (721-815), an [[Alchemy and chemistry in Islam|Arabian alchemist]].<ref>[[George Sarton]], ''Introduction to the History of Science'' ([[cf.]] Dr. A. Zahoor and Dr. Z. Haq (1997), [http://www.cyberistan.org/islamic/Introl1.html ''Quotations From Famous Historians of Science''], [http://www.cyberistan.org Cyberistan])</ref> [[Albertus Magnus]] (Albert the Great, 1193-1280) is believed to have been the first European to isolate the element in 1250.<ref name="BuildingBlocks451-3" /> In 1649, [[Johann Schröder]] published two ways of preparing arsenic. [[Image:Arsenic alchemical symbol.svg|75px|thumb|right|[[Alchemy|Alchemical]] symbol for arsenic]] In the [[Victorian era]], "arsenic" (colourless, crystalline, soluble "white arsenic") was mixed with [[vinegar]] and [[chalk]] and eaten by women to improve the [[complexion]] of their faces, making their skin paler to show they did not work in the fields. Arsenic was also rubbed into the faces and arms of women to "improve their complexion". The accidental use of arsenic in the adulteration of foodstuffs led to [[The Bradford Sweet Poisoning|the Bradford sweet poisoning]] in 1858, which resulted in approximately 20 deaths and 200 people taken ill with arsenic poisoning. ==Occurrence== [[Image:Native arsenic.jpg|right|200px|thumb|A large sample of native arsenic.]] [[Image:Arsenic (white)2.PNG|thumb|right|White arsenic output in 2005]] In 2005, China was the top producer of white arsenic with almost 50% world share followed by Chile and Peru, reports the [[British Geological Survey]]. [[Arsenopyrite]] also unofficially called mispickel ([[iron|Fe]]As[[sulfur|S]]) is the most common arsenic-bearing [[mineral]]. On roasting in air, the arsenic sublimes as arsenic (III) oxide leaving iron oxides. The most important compounds of arsenic are arsenic (III) oxide, As<sub>2</sub>O<sub>3</sub>, ("[[white arsenic]]"), the yellow sulfide [[orpiment]] (As<sub>2</sub>S<sub>3</sub>) and red [[realgar]] (As<sub>4</sub>S<sub>4</sub>), [[Paris Green]], [[calcium arsenate]], and [[lead hydrogen arsenate]]. The latter three have been used as [[agriculture|agricultural]] [[insecticide]]s and [[poison]]s. Orpiment and realgar were formerly used as painting pigments, though they have fallen out of use due to their toxicity and reactivity. Although arsenic is sometimes found native in nature, its main economic source is the mineral [[arsenopyrite]] mentioned above; it is also found in arsenides of metals such as [[silver]], [[cobalt]] (cobaltite: CoAsS and skutterudite: CoAs<sub>3</sub>) and [[nickel]], as [[sulfide]]s, and when oxidised as arsenate minerals such as [[mimetite]], Pb<sub>5</sub>(AsO<sub>4</sub>)<sub>3</sub>Cl and [[erythrite]], Co<sub>3</sub>(AsO<sub>4</sub>)<sub>2</sub>. 8H<sub>2</sub>O, and more rarely arsenites ('arsenite' = arsenate(III), AsO<sub>3</sub><sup>3-</sup> as opposed to arsenate (V), AsO<sub>4</sub><sup>3-</sup>). In addition to the inorganic forms mentioned above, arsenic also occurs in various organic forms in the environment. Inorganic arsenic and its compounds, upon entering the [[food chain]], are progressively metabolised to a less toxic form of arsenic through a process of [[methylation]]. For example certain [[Scopulariopsis brevicaulis|molds]] produce significant amounts of [[trimethylarsine]] if inorganic arsenic is present. The organic compound [[arsenobetaine]] is found in some marine foods such as fish and algae, and also in mushrooms in larger concentrations. The average person's intake is about 10-50 µg/day. Values about 1000 µg are not unusual following consumption of fish or mushrooms. But there is little danger in eating fish because this arsenic compound is nearly non-toxic. ''See also [[:category:Arsenide minerals|Arsenide minerals]], [[:category:Arsenate minerals|Arsenate minerals]].'' ==Toxicity== {{main|Arsenic poisoning}} [[Image:Skull and crossbones.svg|left|80px]] Arsenic and many of its compounds are especially potent poisons. Arsenic disrupts [[Adenosine triphosphate|ATP]] production through several mechanisms. At the level of the [[citric acid cycle]], arsenic inhibits [[pyruvate dehydrogenase]] and by competing with phosphate it uncouples [[oxidative phosphorylation]], thus inhibiting energy-linked reduction of [[Nicotinamide adenine dinucleotide|NAD+]], mitochondrial respiration, and ATP synthesis. Hydrogen peroxide production is also increased, which might form reactive oxygen species and oxidative stress. These metabolic interferences lead to death from multi-system [[organ failure]] (see [[arsenic poisoning]]) probably from [[necrotic]] cell death, not [[apoptosis]]. A [[post mortem]] reveals brick red colored [[mucosa]], due to severe [[hemorrhage]]. Although arsenic causes toxicity, it can also play a protective role.<ref>Casarett and Doull's Essentials of Toxicology 2003</ref>. Elemental arsenic and arsenic compounds are classified as "[[toxicity|toxic]]" and "dangerous for the environment" in the [[European Union]] under [[directive 67/548/EEC]]. <!-- INDEX 033-001-00-X (arsenic) R23/25-50/53; S1/2-20/21-28-45-60-61 --> <!-- INDEX 033-002-00-5 (other compounds) pareil --> The [[IARC]] recognizes arsenic and arsenic compounds as [[List of IARC Group 1 carcinogens|group 1 carcinogens]], and the EU lists [[arsenic trioxide]], [[arsenic pentoxide]] and [[arsenate]] salts as category 1 [[carcinogen]]s. Arsenic is known to cause [[arsenicosis]] due to its manifestation in drinking water, “the most common species being arsenate [HAsO<sub>4</sub><sup>2-</sup> ; As(V)] and arsenite [H<sub>3</sub>AsO<sub>3</sub> ; As(III)]”. The ability of arsenic to undergo redox conversion between As(III) and As(V) makes its availability in the environment possible. According to Croal, Gralnick, Malasarn, and Newman, “[the] understanding [of] what stimulates As(III) oxidation and/or limits As(V) reduction is relevant for bioremediation of contaminated sites (Croal). The study of chemolithoautotrophic As(III) oxidizers and the heterotrophic As(V) reducers can help the understanding of the oxidation and/or reduction of arsenic.<ref>Croal, Laura R., Jeffrey A. Gralnick, Davin Malasarn, and Dianne K. Newman. "The Genetics of Geochemisty." Annual Review of Genetics 38.1 (2004): 175-206. [[24 April]], [[2006]]. <http://web103.epnet.com></ref> ===Arsenic in drinking water=== {{main|Arsenic contamination of groundwater}} [[Arsenic contamination of groundwater]] has led to a massive epidemic of arsenic poisoning in [[Bangladesh]]<ref>Andrew Meharg, Venomous Earth - How Arsenic Caused The World's Worst Mass Poisoning, [http://www.macmillanscience.com/1403944997.htm Macmillan Science], 2005.</ref> and neighbouring countries. It is estimated that approximately 57 million people<!--just Bangladesh, or total?--> are drinking [[groundwater]] with arsenic concentrations elevated above the [[World Health Organization]]'s standard of 10 [[Concentration#.22Parts-per.22 Notation|parts per billion]]. The arsenic in the groundwater is of natural origin, and is released from the sediment into the groundwater due to the anoxic conditions of the subsurface. This groundwater began to be used after western [[Non-governmental organization|NGOs]] instigated a massive tube [[Water well|well]] drinking-water program in the late [[twentieth century]]. This program was designed to prevent drinking of bacterially contaminated surface waters, but failed to test for arsenic in the groundwater.(2) Many other countries and districts in [[Southeast Asia|South East Asia]], such as [[Vietnam]], [[Cambodia]], and [[Tibet]], [[China]], are thought to have geological environments similarly conducive to generation of high-arsenic groundwaters. [[Arsenicosis]] was reported in [[Nakhon Si Thammarat]], [[Thailand]] in 1987, and the dissolved arsenic in the [[Chao Phraya River]] is suspected of containing high levels of naturally occurring arsenic, but has not been a public health problem due to the use of bottled water.<ref>http://wedc.lboro.ac.uk/conferences/pdfs/28/Kohnhorst.pdf</ref> The northern United States, including parts of [[Michigan]], [[Wisconsin]], [[Minnesota]] and the Dakotas are known to have significant concentrations of arsenic in ground water. Increased levels of skin cancer have been associated with arsenic exposure in Wisconsin, even at levels below the 10 part per billion drinking water standard.<ref>{{cite journal |author=Knobeloch LM, Zierold KM, Anderson HA |title=Association of arsenic-contaminated drinking-water with prevalence of skin cancer in Wisconsin's Fox River Valley |journal=J Health Popul Nutr |volume=24 |issue=2 |pages=206–13 |year=2006 |pmid=17195561 |doi=}}</ref> Epidemiological evidence from [[Chile]] shows a dose dependent connection between chronic arsenic exposure and various forms of cancer, particularly when other risk factors, such as cigarette smoking, are present. These effects have been demonstrated to persist below 50 parts per billion. <ref>{{cite journal |author=Ferreccio C, Sancha AM |title=Arsenic exposure and its impact on health in Chile |journal=J Health Popul Nutr |volume=24 |issue=2 |pages=164–75 |year=2006 |pmid=17195557 |doi=}}</ref> A study of cancer rates in Taiwan <ref>{{cite journal |author=Lamm SH, Engel A, Penn CA, Chen R, Feinleib M |title=Arsenic cancer risk confounder in southwest Taiwan data set |journal=Environ. Health Perspect. |volume=114 |issue=7 |pages=1077–82 |year=2006 |pmid=16835062 |doi=}}</ref> suggested that significant increases in cancer mortality appear only at levels above 150 parts per billion. Analyzing multiple epidemiological studies on inorganic arsenic exposure suggests a small but measurable risk increase for bladder cancer at 10 parts per billion.<ref>{{cite journal |author=Chu HA, Crawford-Brown DJ |title=Inorganic arsenic in drinking water and bladder cancer: a meta-analysis for dose-response assessment |journal=Int J Environ Res Public Health |volume=3 |issue=4 |pages=316–22 |year=2006 |pmid=17159272 |doi=}}</ref> According to Peter Ravenscroft of the Department of Geography at the University of Cambridge <ref>{{cite web |url=http://www.usatoday.com/news/world/2007-08-30-553404631_x.htm |title=Arsenic in drinking water seen as threat - USATODAY.com |accessdate=2008-01-01 |format= |work=}}</ref> roughly 80 million people worldwide consume between 10 and 50 parts per billion arsenic in their drinking water. If they all consumed exactly 10 parts per billion arsenic in their drinking water, the previously cited multiple epidemiological study analysis would predict an additional 2,000 cases of bladder cancer alone. This represents a clear underestimate of the overall impact, since it does not include lung or skin cancer, and explicitly underestimates the exposure. Those exposed to levels of arsenic above the current WHO standard should weigh the costs and benefits of arsenic remmediation. Arsenic can be removed from drinking water through [[coprecipitation]] of iron minerals by oxidation and filtering. When this treatment fails to produce acceptable results, adsorptive arsenic removal media may be utilized. Several adsorptive media systems have been approved for point-of-service use in a study funded by the [[United States Environmental Protection Agency]] (U.S.EPA) and the [[National Science Foundation]] (NSF). Magnetic separations of arsenic at very low magnetic field gradients have been demonstrated in point-of-use water purification with high-surface-area and monodisperse [[magnetite]] (Fe<sub>3</sub>O<sub>4</sub>) [[nanocrystals]]. Using the high specific surface area of Fe<sub>3</sub>O<sub>4</sub> [[nanocrystals]] the mass of waste associated with arsenic removal from water has been dramatically reduced. <ref>Yavuz et al., Low-Field Magnetic Separation of Monodisperse Fe<sub>3</sub>O<sub>4</sub> Nanocrystals [http://www.sciencemag.org/cgi/content/full/314/5801/964 Science], 2005.</ref> ===Occupational Exposures=== Exposure to higher-than-average levels of arsenic can occur in some occupations placing workers at risk. Industries that use inorganic arsenic and its compounds include wood preservation, glass production, nonferrous metal alloys, and electronic semiconductor manufacturing. Inorganic arsenic is also found in coke oven emissions associated with the smelter industry. <ref>{{cite web|url= http://www.osha.gov/SLTC/arsenic/index.html |title=OSHA Arsenic |accessdate=2007-10-08|publisher=United States Occupational Safety and Health Administration}}</ref> ==Compounds== *[[Arsenic acid]] (H<sub>3</sub>AsO<sub>4</sub>) *[[Arsenous acid]] (H<sub>3</sub>AsO<sub>3</sub>) *[[Arsenic trioxide]] (As<sub>2</sub>O<sub>3</sub>) *[[Arsine]] (Arsenic Trihydride AsH<sub>3</sub>) *[[Cadmium arsenide]] (Cd<sub>3</sub>As<sub>2</sub>) *[[Gallium arsenide]] (GaAs) *[[Lead hydrogen arsenate]] (PbHAsO<sub>4</sub>) Arsenic also occurs in the II oxidation state, but only in the As<sub>2</sub><sup>4+</sup> cation, As(II) is never found otherwise.<ref>{{cite web|url=http://www.webelements.com/webelements/compounds/text/As/As4S4-12279902.html|title=Arsenic: arsenic(II) sulfide compound data|accessdate=2007-12-10|publisher=WebElements.com}}</ref> ''See also [[:Category:Arsenic compounds|Arsenic compounds]].'' ==Isotopes== {{main|isotopes of arsenic}} Arsenic has been proposed as a "[[Salted bomb|salting]]" material for [[nuclear weapon]]s ([[cobalt]] is another, better-known salting material). A jacket of <sup>75</sup>As, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope <sup>76</sup>As with a [[half-life]] of 1.0778 days and produce approximately 1.13 [[MeV]] of [[Gamma ray|gamma radiation]], significantly increasing the radioactivity of the weapon's [[Nuclear fallout|fallout]] for several hours.{{Fact|date=February 2007}} Such a weapon is not known to have ever been built, tested, or used. ==Notes== {{reflist}} ==References== * [http://periodic.lanl.gov/elements/33.html Los Alamos National Laboratory &ndash; Arsenic] ==See also== * [[Aqua Tofana]] * [[Arsenic poisoning]] * [[Arsenicosis]] * [[Fowler's solution]] * [[Grainger challenge]] * [[Black arsenic]] * [[White arsenic]] ==External links== {{Commons|Arsenic}} {{wiktionarypar|arsenic}} * [http://ctd.mdibl.org/detail.go?type=chem&acc=D001151&queryTerms=arsenic&queryType=contains CTD's Arsenic page] and [http://ctd.mdibl.org/detail.go?type=chem&acc=D001152&queryTerms=arsenicals&queryType=contains CTD's Arsenicals page] from the [[Comparative Toxicogenomics Database]] * [http://www.asmalldoseof.org/ A Small Dose of Toxicology] * [http://www.atsdr.cdc.gov/csem/arsenic/ ATSDR - Case Studies in Environmental Medicine: Arsenic Toxicity] * [http://www.clu-in.org/contaminantfocus/default.focus/sec/arsenic/cat/Overview/ Contaminant Focus: Arsenic] by the [[United States Environmental Protection Agency|EPA]]. * [http://www.inchem.org/documents/ehc/ehc/ehc224.htm Environmental Health Criteria for Arsenic and Arsenic Compounds, 2001] by the [[World Health Organization|WHO]]. * [http://www-cie.iarc.fr/htdocs/monographs/vol23/arsenic.html Evaluation of the carcinogenicity of arsenic and arsenic compounds] by the [[IARC]]. * [http://www.cdc.gov/niosh/topics/arsenic/ National Institute for Occupational Safety and Health - Arsenic Page] * [http://www.npi.gov.au/database/substance-info/profiles/11.html National Pollutant Inventory - Arsenic] * [http://www.origen.net/arsenic.html origen.net &ndash; CCA wood and arsenic: toxicological effects of arsenic] * [http://www.webelements.com/webelements/elements/text/As/index.html WebElements.com &ndash; Arsenic] * [http://www.kfunigraz.ac.at/achwww/Seiten/englische%20Seiten/e_default.htm Institute of Chemistry Karl Franzens University Austria] {{clear}} {{compact periodic table}} [[Category:Metalloids]] [[Category:Pnictogens]] [[Category:Toxicology]] [[Category:Chemical elements]] [[Category:Arsenic| ]] [[Category:Occupational safety and health]] {{Link FA|de}} <!-- interwiki --> {{Link FA|id}} [[af:Arseen]] [[ar:زرنيخ]] [[az:Arsen]] [[bn:আর্সেনিক]] [[be:Мыш'як]] [[bs:Arsen]] [[bg:Арсен]] [[ca:Arsènic]] [[cs:Arsen]] [[co:Arsenicu]] [[cy:Arsenig]] [[da:Arsen]] [[de:Arsen]] [[et:Arseen]] [[el:Αρσενικό (χημικό στοιχείο)]] [[es:Arsénico]] [[eo:Arseno]] [[eu:Artseniko]] [[fa:آرسنیک]] [[fr:Arsenic]] [[fur:Arsenic]] [[ga:Arsanaic]] [[gv:Arsnick]] [[gl:Arsénico]] [[ko:비소]] [[hy:Մկնդեղ]] [[hi:आर्सेनिक]] [[hr:Arsen]] [[io:Arseno]] [[id:Arsen]] [[is:Arsen]] [[it:Arsenico]] [[he:ארסן]] [[jv:Arsenik]] [[pam:Arsenic]] [[sw:Asenia]] [[ht:Asenik]] [[la:Arsenicum]] [[lv:Arsēns]] [[lb:Arsen]] [[lt:Arsenas]] [[jbo:arseniko]] [[hu:Arzén]] [[mr:आर्सेनिक]] [[nl:Arseen]] [[ja:ヒ素]] [[no:Arsen]] [[nn:Arsen]] [[oc:Arsenic]] [[uz:Margimush]] [[nds:Arsen]] [[pl:Arsen]] [[pt:Arsênio]] [[ro:Arsen]] [[qu:Arsiniku]] [[ru:Мышьяк]] [[sc:Arsènicu]] [[stq:Arsen]] [[scn:Arsenicu]] [[simple:Arsenic]] [[sk:Arzén]] [[sl:Arzen]] [[sr:Арсен]] [[sh:Arsenik]] [[fi:Arseeni]] [[sv:Arsenik]] [[ta:ஆர்சனிக்]] [[th:อาร์ซีนิก]] [[vi:Asen]] [[tg:Арсен]] [[tr:Arsenik]] [[uk:Миш'як]] [[ur:زرنیخ]] [[zh:砷]]