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Cadmium - Wikipedia, the free encyclopedia /**/ /**/ if (wgNotice != '') document.writeln(wgNotice); Cadmium From Wikipedia, the free encyclopedia Jump to: navigation, search 48silver ← cadmium → indiumZn↑Cd↓Hg Periodic Table - Extended Periodic TableGeneralName, Symbol, Numbercadmium, Cd, 48Element categorytransition metalsGroup, Period, Block12, 5, dAppearancesilvery gray metallic Standard atomic weight112.411(8) g·mol−1Electron configuration[Kr] 5s2 4d10Electrons per shell2, 8, 18, 18, 2Physical propertiesPhasesolidDensity (near r.t.)8.65 g·cm−3Liquid density at m.p.7.996 g·cm−3Melting point594.22 K(321.07 °C, 609.93 °F)Boiling point1040 K(767 °C, 1413 °F)Heat of fusion6.21 kJ·mol−1Heat of vaporization99.87 kJ·mol−1Specific heat capacity(25 °C) 26.020 J·mol−1·K−1Vapor pressureP(Pa)1101001 k10 k100 kat T(K)5305836547458671040Atomic propertiesCrystal structurehexagonalOxidation states2, 1(mildly basic oxide)Electronegativity1.69 (Pauling scale)Ionization energies1st: 867.8 kJ/mol2nd: 1631.4 kJ/mol3rd: 3616 kJ/molAtomic radius155 pmAtomic radius (calc.)161 pmCovalent radius148 pmVan der Waals radius158 pmMiscellaneousMagnetic orderingno dataElectrical resistivity(22 °C) 72.7 nΩ·mThermal conductivity(300 K) 96.6 W·m−1·K−1Thermal expansion(25 °C) 30.8 µm·m−1·K−1Speed of sound (thin rod)(20 °C) 2310 m/sYoung's modulus50 GPaShear modulus19 GPaBulk modulus42 GPaPoisson ratio0.30Mohs hardness2.0Brinell hardness203 MPaCAS registry number7440-43-9Most-stable isotopesMain article: Isotopes of cadmiumisoNAhalf-lifeDMDE (MeV)DP106Cd1.25%>9.5×1017 yεε2ν-106Pd107Cdsyn6.5 hε1.417107Ag108Cd0.89%>6.7×1017 yεε2ν-108Pd109Cdsyn462.6 dε0.214109Ag110Cd12.49%110Cd is stable with 62 neutrons111Cd12.8%111Cd is stable with 63 neutrons112Cd24.13%112Cd is stable with 64 neutrons113Cd12.22%7.7×1015 yβ-0.316113In113mCdsyn14.1 yβ-0.580113InIT0.264113Cd114Cd28.73%>9.3×1017 yββ2ν-114Sn115Cdsyn53.46 hβ-1.446115In116Cd7.49%2.9×1019 yββ2ν-116SnReferencesCadmium (pronounced /ˈkædmiəm/) is a chemical element with the symbol Cd and atomic number 48. A relatively abundant (price 3.55 USD/lb as of 2008-02-15), soft, bluish-white, transition metal, cadmium is known to cause cancer and occurs with zinc ores. Cadmium is used largely in batteries and pigments, for example in plastic products.Contents1 Characteristics1.1 Chemical1.2 Isotopes2 Applications2.1 Batteries2.2 Other uses3 History4 Occurrence5 Extraction6 Biological role7 Toxicity8 References9 See also10 External links//[edit] CharacteristicsCadmium is a soft, malleable, ductile, toxic, bluish-white bivalent metal. It is similar in many respects to zinc but reacts to form more complex compounds.[edit] ChemicalThe most common oxidation state of cadmium is +2, though rare examples of +1 can be found. Cadmium burns in air and forms a brown amorph cadmium oxide (CdO), the crystalline modification is dark red and changes color when heated, similar to zinc oxide. Hydrochloric acid, sulfuric acid and nitric acid dissolve cadmium by forming cadmium chloride (CdCl2) cadmium sulfate (CdSO4) or cadmium nitrate (Cd(NO3)2). The oxidation state +1 can be reached by dissolving cadmium in a mixture of cadmium chloride and aluminium chloride, forming the Cd22+ which is similar to the Hg22+ in mercury(I) chloride.[1]Cd + CdCl2 + 2AlCl3 → 2Cd[AlCl4][edit] IsotopesMain article: isotopes of cadmiumNaturally occurring cadmium is composed of 8 isotopes. For two of them, natural radioactivity was observed, and three others are predicted to be radioactive but their decays were never observed, due to extremely long half-life times. The two natural radioactive isotopes are 113Cd (beta decay, half-life is 7.7 × 1015 years) and 116Cd (two-neutrino double beta decay, half-life is 2.9 × 1019 years). The other three are 106Cd, 108Cd (double electron capture), and 114Cd (double beta decay); only lower limits on their half-life times have been set. At least three isotopes - 110Cd, 111Cd, and 112Cd - are absolutely stable. Among the isotopes absent in the natural cadmium, the most long-lived are 109Cd with a half-life of 462.6 days, and 115Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives that are less than 2.5 hours, and the majority of these have half-lives that are less than 5 minutes. This element also has 8 known meta states, with the most stable being 113mCd (t½ 14.1 years), 115mCd (t½ 44.6 days), and 117mCd (t½ 3.36 hours).  The cadmium-113 total cross section clearly showing the cadmium cutoff.The known isotopes of cadmium range in atomic mass from 94.950 u (95Cd) to 131.946 u (132Cd). The primary decay mode before the second-most-abundant stable isotope, 112Cd, is electron capture, and the primary modes after are beta emission and electron capture. The primary decay product before 112Cd is element 47 (silver), and the primary product after is element 49 (indium).One particular isotope of cadmium, 113Cd, absorbs neutrons with very high probability if they have an energy below the cadmium cutoff and transmits them readily otherwise. The cadmium cutoff is about 0.5 eV.[2] Neutrons with energy below the cutoff are deemed slow neutrons, distinguishing them from intermediate and fast neutrons.[edit] Applications[edit] Batteries Ni-Cd batteriesAbout three-quarters of cadmium is used in batteries, predominantly in rechargeable nickel-cadmium batteries. Nickel-cadmium cells have a nominal cell potential of 1.2 V. The cell consists of a positive nickel hydroxide electrode plate and a negative cadmium electrode plate separated by an alkaline electrolyte (potassium hydroxide). The next generation of Nickel-metal hydride batteries reduced the use of Ni-Cd batteries. The European Union banned the use of Cadmium in electronics in 2004 with several exceptions but reduced the allowed content of cadmium in electronics to 0.002 %.[3][edit] Other usesMost of the remaining quarter is used mainly for pigments, coatings and plating, and as stabilizers for plastics. Other uses include: Train painted with Cadmium yellowIn some of the lowest-melting alloysIn bearing alloys, due to a low coefficient of friction and very good fatigue resistanceIn electroplating (6% cadmium)In many kinds of solderAs a barrier to control nuclear fissionIn black and white television phosphors and in the blue and green phosphors for color television picture tubesAs a photoconductive surface coating for photocopier drums. (Cadmium Sulphide)In paint pigments: Cadmium forms various Salts, with cadmium sulfide being the most common. This sulfide is used as a yellow pigment. Cadmium selenide can be used as red pigment, commonly called cadmium red. To painters that work with the pigment, cadmium yellows, oranges, and reds are the most potent colours to use. In fact, during production, these colours are significantly toned down before they are ground with oils and binders, or blended into watercolours, gouaches, acrylics, and other paint and pigment formulations. These pigments are toxic, and it is recommended to use a barrier cream on the hands to prevent absorption through the skin when working with them. Cadmium blue, green, and violet do not exist.In some semiconductors such as cadmium sulfide, cadmium selenide, and cadmium telluride, which can be used for light detection or solar cells. HgCdTe is sensitive to infrared.In PVC as stabilizers.In molecular biology, used to block voltage-dependent calcium channels from fluxing calcium ions.See also Category:Cadmium compounds.[edit] HistoryCadmium (Latin cadmia, Greek καδμεία meaning "calamine", a cadmium-bearing mixture of minerals, which was named after the Greek mythological character, Κάδμος Cadmus) was discovered in Germany in 1817 by Friedrich Strohmeyer.[4] Strohmeyer found the new element within an impurity in zinc carbonate (calamine), and, for 100 years, Germany remained the only important producer of the metal. The metal was named after the Latin word for calamine, since the metal was found in this zinc compound. Strohmeyer noted that some impure samples of calamine changed color when heated but pure calamine did not.Even though cadmium and its compounds are highly toxic, the British Pharmaceutical Codex from 1907 states that cadmium iodide was used as a medicine to treat "enlarged joints, scrofulous glands,[5] and chilblains".In 1927, the International Conference on Weights and Measures redefined the meter in terms of a red cadmium spectral line (1m = 1,553,164.13 wavelengths).[6] This definition has since been changed (see krypton).[edit] Occurrence Cadmium metal Cadmium output in 2005 World production trendIn 2001, China was the top producer of cadmium with almost one-sixth world share closely followed by South Korea and Japan, reports the British Geological Survey.Cadmium-containing ores are rare and are found to occur in small quantities. However, traces do naturally occur in phosphate, and have been shown to transmit in food through fertilizer application.[7] Greenockite (CdS), the only cadmium mineral of importance, is nearly always associated with sphalerite (ZnS). As a consequence, cadmium is produced mainly as a byproduct from mining, smelting, and refining sulfide ores of zinc, and, to a lesser degree, lead and copper. Small amounts of cadmium, about 10% of consumption, are produced from secondary sources, mainly from dust generated by recycling iron and steel scrap. Production in the United States began in 1907, but it was not until after World War I that cadmium came into wide use.See also Category:Cadmium minerals.[edit] ExtractionCadmium is a common impurity in zinc, and it is most often isolated during the production of zinc. Zinc sulfide ores are roasted in the presence of oxygen, converting the zinc sulfide to the oxide. Zinc metal is produced either by smelting the oxide with carbon or by electrolysis in sulfuric acid. Cadmium is isolated from the zinc metal by vacuum distillation if the zinc is smelted, or cadmium sulfate is precipitated out of the electrolysis solution.[8][edit] Biological roleA role of cadmium in biology has been recently discovered. A cadmium-dependent carbonic anhydrase has been found in marine diatoms. Cadmium does the same job as zinc in other anhydrases, but the diatoms live in environments with very low zinc concentrations, thus biology has taken cadmium rather than zinc, and made it work. The discovery was made using X-ray absorption fluorescence spectroscopy (XAFS), and cadmium was characterised by noting the energy of the X-rays that were absorbed.[9][10] Image of the violet light from a helium cadmium metal vapor laser. The highly monochromatic color arises from the 441.563 nm transition line of cadmium.[edit] ToxicityMain article: Cadmium poisoningCadmium poisoning is an occupational hazard associated with industrial processes such as metal plating and the production of nickel-cadmium batteries, pigments, plastics, and other synthetics. The primary route of exposure in industrial settings is inhalation. Inhalation of cadmium-containing fumes can result initially in metal fume fever but may progress to chemical pneumonitis, pulmonary edema, and death.[11]Cadmium is also a potential environmental hazard. Human exposures to environmental cadmium are primarily the result of the burning of fossil fuels and municipal wastes.[12] However, there have been notable instances of toxicity as the result of long-term exposure to cadmium in contaminated food and water. In the decades following World War II, Japanese mining operations contaminated the Jinzu River with cadmium and traces of other toxic metals. As a consequence, cadmium accumulated in the rice crops growing along the riverbanks downstream of the mines. The local agricultural communities consuming the contaminated rice developed Itai-itai disease and renal abnormalities, including proteinuria and glucosuria.[13] Cadmium is one of six substances banned by the European Union's Restriction on Hazardous Substances (RoHS) directive, which bans certain hazardous substances in electronics.Cadmium and several cadmium-containing compounds are known carcinogens and can induce many types of cancer.[14]Current research has found that cadmium toxicity may be carried into the body by zinc binding proteins; in particular, proteins that contain zinc finger protein structures. Zinc and cadmium are in the same group on the periodic table, contain the same common oxidation state (+2), and when ionized are almost the same size. Due to these similarities, cadmium can replace zinc in many biological systems, in particular, systems that contain softer ligands such as sulfur. Cadmium can bind up to ten times more strongly than zinc in certain biological systems, and is notoriously difficult to remove. In addition, cadmium can replace magnesium and calcium in certain biological systems, although these replacements are rare.Tobacco smoking is the most important single source of cadmium exposure in the general population. It has been estimated that about 10% of the cadmium content of a cigarette is inhaled through smoking. The absorption of cadmium from the lungs is much more effective than that from the gut, and as much as 50% of the cadmium inhaled via cigarette smoke may be absorbed.[15]On average, smokers have 4-5 times higher blood cadmium concentrations and 2-3 times higher kidney cadmium concentrations than non-smokers. Despite the high cadmium content in cigarette smoke, there seems to be little exposure to cadmium from passive smoking. No significant effect on blood cadmium concentrations could be detected in children exposed to environmental tobacco smoke.[edit] References^ Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils; (1985). Lehrbuch der Anorganischen Chemie, 91–100 (in German), Walter de Gruyter, 1056–1057. ISBN 3-11-007511-3. ^ Knoll, G.F. (1999). Radiation Detection and Measurement, 3rd edition. Wiley. ISBN 978-0471073383. p505^ "Batteries to be collected and recycled, nature protected". Retrieved on 2008-11-04.^ Hermann; Strohmeyer F. (1818). "Noch ein schreiben über das neue Metall (Another letter about the new metal)". Annalen der Physik 59: 113, http://gallica.bnf.fr/ark:/12148/bpt6k150680/f125.chemindefer. ^ Dunglison, Robley (1866). Medical Lexicon: A Dictionary of Medical Science. Henry C. Lea, 159. ^ Burdun, G. D. (1958). "On the new determination of the meter" (pdf). Measurement Techniques 1 (3): 259–264. doi:10.1007/BF00974680, http://www.springerlink.com/content/tk70442064438147/fulltext.pdf?page=1. ^ Jiao, You; Grant, Cynthia A.; Bailey, Loraine D.. "Effects of phosphorus and zinc fertilizer on cadmium uptake and distribution in flax and durum wheat". Journal of the Science of Food and Agriculture 84 (8): 777–785. doi:10.1002/jsfa.1648. ^ Cadmium at WebElements.com^ Lane, Todd W.; Morel, François M. M. (2000). "A biological function for cadmium in marine diatoms". Proc. Natl. Acad. Sci. 97 (9): 4627-4631. doi:10.1073/pnas.090091397, http://www.pnas.org/content/97/9/4627.full.pdf+html. ^ Lane, Todd W. ,; Saito, Mak A.; George, Graham N.; Pickering, Ingrid J.; Prince, Roger C.; Morel, François M. M. (2005). "A cadmium enzyme from a marine diatom". Nature 435 (42). doi:10.1038/435042a, http://www.whoi.edu/cms/files/msaito/2005/5/LaneSaitoMorel_CdCA_Nature2005_2944.pdf. ^ [1] Principles and Methods of Toxicology (fourth edition). A. Wallace Hayes. Taylor and Francis Publishing Inc.; Philadelphia, 2001.^ EPA summary on cadmium^ [2] Environmental cadmium exposure, adverse effects, and preventative measures in Japan. Nogowa et al. Biometals. 2004 Oct; 17(5):581-7.^ 11th Report on Carcinogens provided by the National Toxicology Program^ Friberg, L. (1983). "Cadmium". Annual Review of Public Health 4: 367–367. doi:10.1146/annurev.pu.04.050183.002055. [edit] See alsoList of breast carcinogenic substances[edit] External links Look up cadmium in Wiktionary, the free dictionary. Wikimedia Commons has media related to:Cadmium Wikisource has the text of the 1911 Encyclopædia Britannica article Cadmium.ATSDR Case Studies in Environmental Medicine: Cadmium Toxicity U.S. Department of Health and Human ServicesIARC Monograph "Cadmium and Cadmium Compounds"National Pollutant Inventory - Cadmium and compoundsWebElements.com – CadmiumLos Alamos National Laboratory – Cadmium[3] Warning Moose and Deer LiverNational Institute for Occupational Safety and Health - Cadmium PageUSGS Comodity Report cadmiumv • d • ePeriodic tableH HeLiBe BCNOFNeNaMg AlSiPSClArKCa ScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSr YZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRnFrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgUubUutUuqUupUuhUusUuoUueUbn Alkali metalsAlkaline earth metalsLanthanoidsActinoidsTransition metalsOther metalsMetalloidsOther nonmetalsHalogensNoble gasesRetrieved from "http://en.wikipedia.org/wiki/Cadmium" Categories: Chemical elements | Transition metals | Toxicology | IARC Group 1 carcinogens | Soil contamination | Cadmium | Occupational safety and health Views Article Discussion Edit this page History Personal tools Log in / create account if (window.isMSIE55) fixalpha(); Navigation Main page Contents Featured content Current events Random article Search Interaction About Wikipedia Community portal Recent changes Contact Wikipedia Donate to Wikipedia Help Toolbox What links here Related changesUpload fileSpecial pages Printable version Permanent linkCite this page Languages Afrikaans العربية বাংলা Беларуская Bosanski Català Česky Corsu Cymraeg Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Furlan Gaeilge Gaelg Galego 한국어 Հայերեն हिन्दी Hrvatski Ido Bahasa Indonesia Íslenska Italiano עברית Basa Jawa ಕನ್ನಡ Kiswahili Kreyòl ayisyen Kurdî / كوردی Latina Latviešu Lëtzebuergesch Lietuvių Lojban Magyar മലയാളം Nederlands 日本語 Norsk (bokmål) Norsk (nynorsk) Occitan O'zbek Plattdüütsch Polski Português Română Runa Simi Русский Shqip Sicilianu Simple English Slovenčina Slovenščina Српски / Srpski Srpskohrvatski / Српскохрватски Seeltersk Suomi Svenska தமிழ் ไทย Tiếng Việt Türkçe Українська 中文   This page was last modified on 21 November 2008, at 04:57. 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