Cobalt 5670 224673631 2008-07-09T22:27:06Z Thijs!bot 1392310 robot Adding: [[nds:Kobalt]] {{otheruses}} {{mergefrom|Cobalt Poisoning|date=February 2008}} {{Infobox cobalt}} '''Cobalt''' ({{pronEng|ˈkoʊbɒlt}}) is a hard, lustrous, silver-grey [[metal]], a [[chemical element]] with symbol '''Co'''. It is found in various [[ore]]s, and is used in the preparation of [[magnetism|magnetic]], wear-resistant, and high-strength [[alloy]]s. Its [[chemical compound|compound]]s are used in the production of [[ink]]s, [[paint]]s, and [[varnish]]es. == Notable characteristics == <!-- Deleted image removed: [[Image:Cobalt 06.jpg |thumb|left|An electron beam melted sample of cobalt metal made by Kaistar R&D]] --> Cobalt is a silver or gray [[ferromagnetic]] metal. Pure cobalt is not found in nature, but compounds of cobalt occur naturally in many forms. Small amounts of it are found in most rocks, soil, water, plants, and animals. It is the element of atomic number 27. The [[Curie temperature]] is 1388 K with 1.6~1.7 [[Bohr magneton]]s per [[atom]]. In nature, it is frequently associated with [[nickel]], and both are characteristic ingredients of [[meteoric iron]]. [[Mammals]] require small amounts of cobalt which is the basis of [[Cyanocobalamin|vitamin B{{ssub|12}}]]. [[Cobalt-60]], an artificially produced [[radioactive isotope]] of cobalt, is an important [[radioactive tracer]] and [[cancer]]-treatment agent. Cobalt has a [[Permeability (electromagnetism)|relative permeability]] two thirds that of iron. [[Metallic]] cobalt commonly presents a mixture of two [[crystallographic structure]]s [[Hexagonal close packed|hcp]] and [[Face-centered cubic|fcc]] with a [[transition]] temperature hcp→fcc of 722 K. Cobalt has a hardness of 5.5 on the [[Mohs scale of mineral hardness]].{{Fact|date=October 2007}} Common [[oxidation states]] of cobalt include +2 and +3, although compounds with oxidation state +1 are also well developed. ==Isotopes== {{main|Isotopes of cobalt}} Naturally occurring cobalt is "monoisotopic"; i.e. only one [[isotope]] is stable: <sup>59</sup>Co. 22 [[radioisotope]]s have been characterized with the most stable being <sup>60</sup>Co with a [[half-life]] of 5.2714 years, <sup>57</sup>Co with a half-life of 271.79 days, <sup>56</sup>Co with a half-life of 77.27 days, and <sup>58</sup>Co with a half-life of 70.86 days. All of the remaining [[radioactive]] isotopes have half-lives that are less than 18 hours and the majority of these have half-lives that are less than 1 second. This element also has 4 [[meta state]]s, all of which have half-lives less than 15 minutes. The isotopes of cobalt range in [[atomic weight]] from 50 [[atomic mass unit|u]] (<sup>50</sup>Co) to 73 u (<sup>73</sup>Co). The primary [[decay mode]] for isotopes with atomic mass unit values less than that of the most abundant stable isotope, <sup>59</sup>Co, is [[electron capture]] and the primary mode of decay for those of greater than 59 atomic mass units is [[beta decay]]. The primary [[decay product]]s before <sup>59</sup>Co are element 26 ([[iron]]) isotopes and the primary products after are element 28 ([[nickel]]) [[isotopes]]. ====Cobalt radioisotopes in medicine ==== [[Cobalt-60 (isotope)|Cobalt-60 (Co-60 or <sup>60</sup>Co)]] is a [[radioactive]] metal that is used in [[radiation therapy|radiotherapy]]. It produces two [[gamma ray]]s with energies of 1.17 [[MeV]] and 1.33 [[MeV]]. The <sup>60</sup>Co source is about 2 [[centimetre|cm]] in [[diameter]] and as a result produces a [[geometric]] [[penumbra]], making the edge of the [[radiation]] field fuzzy. The metal has the unfortunate habit of producing a fine dust, causing problems with [[radiation protection]]. Cobalt-60 has a radioactive half-life of 5.27 years. This decrease in activity requires periodic replacement of the sources used in radiotherapy. This is one more reason why cobalt machines have been largely replaced by linear accelerators ([[linacs]]) in modern radiation therapy. Cobalt-57 (Co-57 or <sup>57</sup>Co) is a [[radioactive]] metal that is used in medical tests; it is used as a radiolabel for vitamin B{{ssub|12}} uptake. It is useful for the [[Schilling test]].<ref>[http://www.med.harvard.edu/JPNM/physics/isotopes/Co/Co57/uses.html JPNM Physics Isotopes] </ref> ====Industrial uses for radioactive isotopes==== Cobalt-60 (Co-60 or <sup>60</sup>Co) is useful as a [[gamma ray]] source because it can be produced—in predictable quantity, and high [[activity]]—by simply exposing natural cobalt to [[neutron]]s in a reactor for a given time. It is used for *sterilization of medical supplies, and medical waste; *[[radiation]] treatment of [[food irradiation|foods for sterilization]] (cold [[pasteurization]]); *industrial [[radiography]] (e.g., weld integrity radiographs); *density measurements (e.g., concrete density measurements); and *tank fill height switches. Cobalt-59 is used as a source in [[Mössbauer spectroscopy]]. == Applications == * [[Alloy]]s, such as ** [[Superalloy]]s, for parts in gas [[turbine]] [[aircraft]] [[engine]]s. ** [[Corrosion]]- and wear-resistant alloys. ** [[High speed steel]]s. ** Cemented [[carbide]]s (also called hard metals) and [[diamond]] tools. * [[Magnet]]s and magnetic [[recording media]]. ** [[Alnico]] magnets. ** [[Samarium-cobalt magnet]]s. * [[Catalyst]]s for the [[petroleum]] and chemical industries, e.g. for [[hydroformylation]] and [[oxidation]]. * [[Electroplating]] because of its appearance, hardness, and resistance to [[oxidation]]. * Drying agents for [[paint]]s, [[varnish]]es, and [[ink]]s. * Ground coats for [[porcelain]] [[vitreous enamel|enamel]]s. * Pigments ([[cobalt blue]] and [[cobalt green]]). [[Image:bristol.blue.glass.arp.750pix.jpg|thumb|left|145px|Cobalt blue glass]] <br clear="left" style="clear:left" /> * [[Lithium ion battery|Lithium ion]] [[Battery (electricity)|battery]] electrodes. * Steel-belted radial [[tire]]s. * Purification of [[histidine-tag]]ged [[fusion protein]]s in [[biotechnology]] applications. == History == Cobalt compounds have been used for centuries to impart a rich blue color to [[glass]], [[ceramic glaze|glazes]], and [[Ceramics (art)|ceramics]]. Cobalt has been detected in Egyptian sculpture and Persian jewelry from the third millennium BC, in the ruins of [[Pompeii]] (destroyed AD 79), and in [[China]] dating from the [[Tang dynasty]] (AD 618–907) and the [[Ming dynasty]] (AD 1368–1644)<ref>Encyclopedia Britannica Online.</ref>. Cobalt glass ingots have been recovered from shipwrecks dating to the time of the [[Minoan civilization|Minoans]] {{Fact|date=March 2007}} (BC 2700-1450). Swedish chemist [[George Brandt]] (1694–1768) is credited with [[isolating]] cobalt in 1735. He was able to show that cobalt was the source of the blue color in glass, which previously had been attributed to the [[bismuth]] found with cobalt. During the 19th century, cobalt blue was produced at the Norwegian [[Blaafarveværket]] (70-80% of world production), led by the [[Prussia]]n industrialist [[Benjamin Wegner]]. In 1938, John Livingood and [[Glenn Seaborg]] discovered [[cobalt-60]]. The word ''cobalt'' is derived from the German ''kobalt'', from ''[[kobold]]'' meaning "goblin", a term used for the [[ore]] of cobalt by miners. The first attempts at smelting the cobalt ores to produce cobalt metal failed, yielding cobalt(II) oxide instead; not only that, but because of cobalt's curious affinity for [[arsenic]], the primary ores of cobalt always contain arsenic, and upon smelting the arsenic oxidized into the highly toxic As<sub>4</sub>O<sub>6</sub>, which was breathed in by workers. == Occurrence == [[Image:Cobalt OreUSGOV.jpg|thumb|left|150px|Cobalt ore]] [[Image:2005cobalt (mined).PNG|thumb|right|Cobalt output in 2005]] [[Image:Cobalt - world production trend.svg|thumb|World production trend]] Cobalt is not found as a [[native metal]] but generally found in the form of [[ore]]s. Cobalt is usually not mined alone, and tends to be produced as a [[by-product]] of [[nickel]] and [[copper]] mining activities. The main ores of cobalt are [[cobaltite]], [[erythrite]], [[glaucodot]], and [[skutterudite]]. In 2005, the [[Democratic Republic of the Congo]] was the top producer of cobalt with almost 40% world share followed by Canada, Zambia, Russia, Brazil and Cuba, reports the [[British Geological Survey]]. == Compounds == There is a wide variety of cobalt compounds. The +2 and +3 [[oxidation state]]s are most prevalent, however cobalt(I) complexes are also fairly common. Cobalt(II) salts form the red-pink [Co(OH<sub>2</sub>)<sub>6</sub>]<sup>2+</sup> complex in aqueous solution. Adding excess chloride will also change the color from pink to blue, due to the formation of [CoCl<sub>4</sub>]<sup>2-</sup>. Cobalt oxides are [[antiferromagnetic]] at low [[temperature]]: CoO ([[Neel temperature]] 291 K) and Co<sub>3</sub>O<sub>4</sub> (Neel temperature: 40 K), which is analogous to [[magnetite]] (Fe<sub>3</sub>O<sub>4</sub>), with a mixture of +2 and +3 oxidation states. The oxide Co<sub>2</sub>O<sub>3</sub> is probably unstable; it has never been synthesized. Other than Co<sub>3</sub>O<sub>4</sub> and the brown fluoride CoF<sub>3</sub> (which is instantly [[hydrolysis|hydrolyzed]] in water), all compounds containing cobalt in the +3 oxidation state are stabilized by complex ion formation. ; see also [[:Category:Cobalt compounds]] == Biological role == Cobalt in small amounts is essential to many living [[organism]]s, including [[humans]]. Having 0.13 to 0.30 mg/kg of cobalt in soils markedly improves the health of [[grazing]] animals. Cobalt is a central component of the [[vitamin]] [[cobalamin]], or [[Cyanocobalamin|vitamin B{{ssub|12}}]]. == Isotopes == [[Cobalt-60 (isotope)|<sup>60</sup>Co]] is a high-energy [[gamma ray]] emitter. Acute high-dose exposures to the gamma emissions can cause severe burns and death. Extended exposures increase the risk of morbidity or mortality from cancer.<ref>[http://query.nytimes.com/gst/fullpage.html?sec=health&res=9501E7D71338F932A35756C0A962948260 The Juarez accident]</ref> [[Nuclear weapon design]]s could intentionally incorporate <sup>59</sup>Co, some of which would be activated in a nuclear explosion to produce <sup>60</sup>Co. The <sup>60</sup>Co, dispersed as [[nuclear fallout]], creates what is sometimes called a [[dirty bomb]] or [[cobalt bomb]]. == Precautions == Although cobalt is an essential element for life in minute amounts, at higher levels of exposure it shows [[mutagenic]] and [[carcinogenic]] effects similar to [[nickel#Precautions|nickel]] (see [[Cobalt Poisoning]] ).<ref>[http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s048zcob.pdf 11th ROC: Cobalt Sulfate<!-- Bot generated title -->]</ref> Powdered cobalt in metal form is a fire hazard. ==References & notes== *[http://periodic.lanl.gov/elements/27.html Los Alamos National Laboratory: Cobalt] <references/> == External links == {{Commons|Cobalt}} {{wiktionary|cobalt}} * [http://www.npi.gov.au/database/substance-info/profiles/26.html National Pollutant Inventory - Cobalt fact sheet] * [http://www.webelements.com/webelements/elements/text/Co/key.html WebElements.com &ndash; Cobalt] * [http://www.caro-acro.ca/caro/educ/publ/vig/vignettes/cobalt/Interactions.pdf London celebrates 50 years of Cobalt-60 Radiotherapy ] {{clear}} {{Compact periodic table}} [[Category:Chemical elements]] [[Category:Dietary minerals]] [[Category:Transition metals]] [[Category:Cobalt|*]] [[Category:Ferromagnetic materials]] <!-- interwiki --> [[af:Kobalt]] [[ar:كوبالت]] [[az:Kobalt]] [[bn:কোবাল্ট]] [[be:Кобальт]] [[bs:Kobalt]] [[bg:Кобалт]] [[ca:Cobalt]] [[cv:Кобальт]] [[cs:Kobalt]] [[co:Cobaltu]] [[da:Kobolt]] [[de:Cobalt]] [[et:Koobalt]] [[el:Κοβάλτιο]] [[es:Cobalto]] [[eo:Kobalto]] [[eu:Kobalto]] [[fa:کبالت]] [[fr:Cobalt]] [[fur:Cobalt]] [[ga:Cóbalt]] [[gv:Cobalt]] [[gl:Cobalto]] [[ko:코발트]] [[hy:Կոբալտ]] [[hi:कोबाल्ट]] [[hr:Kobalt]] [[io:Kobalto]] [[id:Kobal]] [[is:Kóbolt]] [[it:Cobalto]] [[he:קובלט]] [[kn:ಕೊಬಾಲ್ಟ್]] [[sw:Kobalti]] [[ku:Kobalt]] [[la:Cobaltum]] [[lv:Kobalts]] [[lb:Kobalt]] [[lt:Kobaltas]] [[jbo:ridjinme]] [[hu:Kobalt]] [[mk:Кобалт]] [[ml:കൊബാള്‍ട്ട്]] [[mr:कोबाल्ट]] [[nl:Kobalt]] [[ja:コバルト]] [[no:Kobolt]] [[nn:Kobolt]] [[oc:Cobalt]] [[uz:Kobalt]] [[nds:Kobalt]] [[pl:Kobalt]] [[pt:Cobalto]] [[ro:Cobalt]] [[qu:Kubaltu]] [[ru:Кобальт]] [[stq:Cobalt]] [[simple:Cobalt]] [[sk:Kobalt]] [[sl:Kobalt]] [[sr:Кобалт]] [[sh:Kobalt]] [[fi:Koboltti]] [[sv:Kobolt]] [[th:โคบอลต์]] [[vi:Coban]] [[tg:Кобалт]] [[tr:Kobalt]] [[uk:Кобальт]] [[zh:钴]]