Manganese 19051 226165569 2008-07-17T03:09:08Z Baby Jane 576249 {{Infobox manganese}} '''Manganese''' ({{pronEng|ˈmæŋgəniːz}}) is a [[chemical element]], designated by the symbol '''Mn'''. It has the [[atomic number]] 25. It is found as a [[free element]] in nature (often in combination with iron), and in many minerals. As a free element, Manganese is a metal with important industrial metal alloy uses. Manganese ions are variously colored, and are used industrially as [[pigment]]s and as oxidation chemicals. Manganese (II) ions function as [[cofactor (biochemistry)|cofactor]]s for a number of enzymes; the element is thus a required trace mineral for all known living organisms. == Notable chemical characteristics == [[Image:Mangan 1.jpg|thumb|120px|left|Manganese]] Manganese is a gray-white [[metal]], resembling iron. It is a hard metal and is very brittle, fusible with difficulty, but easily oxidized. Manganese metal and its common ions are [[paramagnetic]]. While manganese metal does not form a permanent magnet, it does exhibit strong magnetic properties in the presence of an external magnetic field. The most common [[oxidation state]]s of manganese are +2, +3, +4, +6 and +7, though oxidation states from +1 to +7 are observed. Mn<sup>2+</sup> often competes with Mg<sup>2+</sup> in biological systems, and manganese compounds where manganese is in oxidation state +7 are powerful [[oxidation|oxidizing agents]]. ==Industrially important compounds== [[Methylcyclopentadienyl manganese tricarbonyl]] is used as an additive in [[unleaded gasoline]] to boost [[octane rating]] and reduce [[engine knocking]]. The manganese in this unusual organometallic compound is in the +1 oxidation state. The most stable oxidation state for manganese is +2, which has a pink to red color, and many manganese(II) compounds are known, such as [[manganese(II) sulfate]] (MnSO<sub>4</sub>) and [[manganese(II) chloride]] (MnCl<sub>2</sub>). This oxidation state is also seen in the mineral [[rhodochrosite]], ([[manganese(II) carbonate]]). The +2 oxidation state is the state use in living organisms for essential functions; all of the other states are much more toxic. The +3 oxidation state is known, in compounds such as [[manganese(III) acetate]], but these are quite powerful [[Redox|oxidizing agents]]. [[Manganese(IV) oxide]] (manganese dioxide, MnO<sub>2</sub>) is used as a reagent in [[organic chemistry]] for the [[oxidation]] of benzylic [[alcohols]] (i.e. adjacent to an [[aromatic ring]]). [[Manganese(IV) oxide|Manganese dioxide]] has been used since antiquity to oxidatively neutralize the greenish tinge in glass caused by trace amounts of iron contamination. MnO<sub>2</sub> is also used in the manufacture of oxygen and chlorine, and in drying black paints. In some preparations it is a brown [[pigment]] that can be used to make [[paint]] and is a constituent of natural [[umber]]. [[Manganese(IV) oxide]] was used in the original type of [[dry cell]] [[Battery (electricity)|battery]] as an electron acceptor from zinc, and is the blackish material found when opening carbon-zinc type flashlight cells. The same material also functions in newer [[alkaline batteries]] (usually battery cells), which use the same basic reaction, but a different electrolyte mixture. [[Parkerize|Manganese phosphating]] is used as a treatment for rust and corrosion prevention on steel. Permanganate (+7 oxidation state) manganese compounds are purple, and can color glass an amethyst color. [[Potassium permanganate]], [[sodium permanganate]] and [[barium permanganate]] are all potent oxidizers. [[Potassium permanganate]], also called [[Condy's crystals]], is a commonly used laboratory [[reagent]] because of its oxidizing properties and finds use as a topical medicine (for example, in the treatment of fish diseases). Solutions of potassium permanganate were among the first stains and fixatives to be used in the preparation of biological cells and tissues for electron microscopy<ref>Luft, JH (1956) Permanganate - a new fixative for electron microscopy. Journal of Biophysical and Biochemical Cytology 2, 799-802</ref>. '''Substitutes:''' Manganese has no satisfactory substitute in its major applications, which are related to metallurgical alloy use. In minor applications, (e.g., [[Parkerize|manganese phosphating]]), [[zinc]] and sometimes [[vanadium]] are viable substitutes. In disposable battery manufacture, standard and alkaline cells using manganese will probably eventually be mostly replaced with [[lithium battery]] technology. The overall level and nature of manganese use in the United States is expected to remain about the same in the near term. No practical technologies exist for replacing manganese with other materials or for using domestic deposits or other accumulations to reduce the complete dependence of the United States on other countries for manganese ore. == Metal alloys== [[Image:Managnese in water pourbiax diagram.png|thumb|left|The [[Pourbaix diagram]] for manganese in pure water, perchloric acid or sodium hydroxide<ref name="medusa">Ignasi Puigdomenech, ''Hydra/Medusa Chemical Equilibrium Database and Plotting Software'' (2004) KTH Royal Institute of Technology, freely downloadable software at [http://www.kemi.kth.se/medusa/]</ref>]] Manganese is essential to iron and [[steelmaking|steel production]] by virtue of its sulfur-fixing, [[deoxidizing]], and [[alloying]] properties. [[Steelmaking]], including its ironmaking component, has accounted for most manganese demand, presently in the range of 85% to 90% of the total demand. Among a variety of other uses, manganese is a key component of low-cost [[stainless steel]] formulations and certain widely used [[aluminium]] alloys. The metal is very occasionally used in coins; the only United States coins to use manganese were the [[Nickel (United States coin)#Wartime nickels|"wartime" nickel]] from 1942&ndash;1945, and, since 2000, [[Dollar (United States coin)|dollar coins]]. The EU uses manganese in 1 and 2 Euro coins, due to greater and cheaper availability. == History == The origin of the name manganese is complex. In ancient times, two black minerals from [[Magnesia]] in what is now modern Greece were both called ''magnes'', but were thought to differ in gender. The male ''magnes'' attracted iron, and was the iron ore we now know as [[lodestone]] or [[magnetite]], and which probably gave us the term [[magnet]]. The female ''magnes'' ore did not attract iron, but was used to decolorize glass. This feminine ''magnes'' was later called ''magnesia'', known now in modern times as [[pyrolusite]] or [[manganese dioxide]]. This mineral is never magnetic (although manganese itself is [[paramagnetic]]). In the 16th century, the latter compound was called ma'''n'''ga'''n'''esum (note the two n's instead of one) by glassmakers, possibly as a corruption of two words since alchemists and glassmakers eventually had to differentiate a ''magnesia negra'' (the black ore) from ''magnesia alba'' (a white ore, also from Magnesia, also useful in glassmaking). Mercati called magnesia negra ''Manganesa'', and finally the metal isolated from it became known as '''manganese''' (German: Mangan). The name ''magnesia'' eventually was then used to refer only to the white magnesia alba (magnesium oxide), which provided the name [[magnesium]] for that free element, when it was eventually isolated, much later. <ref>[http://www.du.edu/~jcalvert/phys/chromang.htm Chromium and Manganese<!-- Bot generated title -->]</ref> Manganese compounds were in use in prehistoric times; paints that were pigmented with [[Manganese(IV) oxide|manganese dioxide]] can be traced back 17,000 years. The Egyptians and Romans used manganese compounds in glass-making, to either remove color from glass or add color to it. Manganese can be found in the iron ores used by the [[Sparta]]ns. Some speculate that the exceptional hardness of Spartan steels derives from the inadvertent production of an iron-manganese alloy. In the 17th century, German chemist [[Johann Glauber]] first produced [[permanganate]], a useful laboratory reagent (although some people believe that it was discovered by [[Ignites Kaim]] in 1770). By the mid-18th century, [[Manganese(IV) oxide|manganese dioxide]] was in use in the manufacture of chlorine (which it produces when mixed with [[hydrochloric acid]], or commercially with a mixture of dilute [[sulfuric acid]] and sodium chloride). The Swedish chemist [[Carl Wilhelm Scheele|Scheele]] was the first to recognize that manganese was an element, and his colleague, [[Johan Gottlieb Gahn]], isolated the pure element in 1774 by reduction of the dioxide with [[carbon]]. Around the beginning of the 19th century, scientists began exploring the use of manganese in steelmaking, with patents being granted for its use at the time. In 1816, it was noted that adding manganese to iron made it harder, without making it any more brittle. In 1837, British academic [[James Couper]] noted an association between heavy exposure to manganese in mines with a form of [[Parkinson's Disease]]. In 1912, [[Parkerize|manganese phosphating]] electrochemical conversion coatings for protecting firearms against rust and corrosion were patented in the United States, and have seen widespread use ever since. In the 20th century, [[manganese(IV) oxide|manganese dioxide]] has seen wide commercial use as the chief cathodic material for commercial disposable [[dry cell]]s and dry batteries of both the standard (carbon-zinc) and alkaline type. == Biological role == Manganese is an essential trace nutrient in all forms of life. The classes of enzymes that have manganese [[Cofactor (biochemistry)|cofactor]]s are very broad and include such classes as [[oxidoreductases]], [[transferases]], [[hydrolases]], [[lyases]], [[isomerases]], [[ligases]], [[lectins]], and [[integrins]]. The [[reverse transcriptase]]s of many [[retrovirus]]es (though not [[lentivirus]]es such as [[HIV]]) contain manganese. The best known manganese-containing [[polypeptides]] may be [[arginase]], the [[diphtheria toxin]], and Mn-containing [[superoxide dismutase]] ([[Mn-SOD]]). Mn-SOD is the type of SOD present in eukaryotic mitochondria, and also in most bacteria (this fact is in keeping with the bacterial-origin theory of mitochondria). The Mn-SOD enzyme is probably one of the most ancient, for nearly all organisms living in the presence of oxygen use it to deal with the toxic effects of [[superoxide]], formed from the 1-electron reduction of dioxygen. Exceptions include a few kinds of bacteria such as [[Lactobacillus plantarum]] and related [[lactobacillus|lactobacilli]], which use a different non-enzymatic mechanism, involving manganese (Mn<sup>2+</sup>) ions complexed with polyphosphate directly for this task, indicating how this function possibly evolved in aerobic life. The human body contains about 10 mg of manganese,which is stored mainly in liver & kidneys. Manganese is also important in photosynthetic [[oxygen evolution]] in [[chloroplast]]s in plants, which are also evolutionarily of bacterial origin. The [[oxygen evolving complex]] (OEC), a water-oxidizing enzyme contained in chloroplast membrane, and which is involved in the terminal [[Oxygen evolution|photooxidation of water]] during the [[light reactions]] of [[photosynthesis]], has a metalloenzyme core containing four atoms of manganese<ref>[http://mrw.interscience.wiley.com/emrw/9780470862100/eic/article/ia128/current/abstract] Accessed Jan 5, 2008</ref> For this reason, most broad-spectrum plant fertilizers contain manganese. == Occurrence == [[Image:ManganeseOreUSGOV.jpg|thumb|Manganese ore]] Manganese occurs principally as [[pyrolusite]] ([[manganese(IV) oxide|MnO<sub>2</sub>]]), [[braunite]], (Mn<sup>2+</sup>Mn<sup>3+</sup>6SiO<sub>12</sub>), [[psilomelane]] (Ba(Mn<sup>2+</sup>)(Mn<sup>4+</sup>)<sub>8</sub>O<sub>16</sub>(OH)<sub>4</sub>), and to a lesser extent as [[rhodochrosite]] ([[manganese(II) carbonate|MnCO<sub>3</sub>]]). Land-based resources are large but irregularly distributed; those of the United States are very low grade and have potentially high extraction costs. Over 80% of the known world manganese resources are found in South Africa and Ukraine. Other important manganese deposits are in China, Australia, Brazil, Gabon, India, and Mexico. [[Image:Mineraly.sk - psilomelan.jpg|thumb| Psilomelane (manganese ore)]] [[Image:Dendrites01.jpg|thumb|Manganese oxide dendrites on a limestone bedding plane from [[Solingen]], Germany. Scale in mm. A kind of [[pseudofossil]].]] US Import Sources (1998–2001): Manganese ore: Gabon, 70%; South Africa, 10%; Australia, 9%; Mexico, 5%; and other, 6%. Ferromanganese: South Africa, 47%; France, 22%; Mexico, 8%; Australia, 8%; and other, 15%. Manganese contained in all manganese imports: South Africa, 31%; Gabon, 21%; Australia, 13%; Mexico, 8%; and other, 27%. Manganese is mined in [[Australia]], [[Burkina Faso]], [[Brazil]] and [[Gabon]]. Vast quantities of manganese exist in [[manganese nodule]]s on the [[ocean floor]]. Attempts to find economically viable methods of harvesting manganese nodules were abandoned in the 1970s. ''See also [[:category:Manganese minerals|manganese minerals]].'' == Isotopes == {{Main|Isotopes of manganese}} Naturally occurring manganese is composed of 1 stable [[isotope]]; <sup>55</sup>Mn. 18 [[radioisotope]]s have been characterized with the most stable being <sup>53</sup>Mn with a [[half-life]] of 3.7 million years, <sup>54</sup>Mn with a half-life of 312.3 days, and <sup>52</sup>Mn with a half-life of 5.591 days. All of the remaining [[radioactive]] isotopes have half lives that are less than 3 hours and the majority of these have half lives that are less than 1 minute. This element also has 3 [[meta state]]s. Manganese is part of the [[iron]] group of elements which are thought to be synthesized in large [[star]]s shortly before [[supernova]] explosion. <sup>53</sup>Mn decays to <sup>53</sup>[[chromium|Cr]] with a [[half-life]] of 3.7 million years. Because of its relatively short half-life, <sup>53</sup>Mn is an extinct [[radionuclide]]. Manganese isotopic contents are typically combined with [[chromium]] isotopic contents and have found application in [[isotope geology]] and [[radiometric dating]]. Mn-Cr isotopic ratios reinforce the evidence from <sup>26</sup>[[Aluminium|Al]] and <sup>107</sup>[[Palladium|Pd]] for the early history of the [[solar system]]. Variations in <sup>53</sup>Cr/<sup>52</sup>Cr and Mn/Cr ratios from several [[meteorite]]s indicate an initial <sup>53</sup>Mn/<sup>55</sup>Mn ratio that suggests Mn-Cr isotopic systematics must result from in-situ decay of <sup>53</sup>Mn in differentiated planetary bodies. Hence <sup>53</sup>Mn provides additional evidence for [[nucleosynthesis|nucleosynthetic]] processes immediately before coalescence of the [[solar system]]. The isotopes of manganese range in [[atomic weight]] from 46 [[atomic mass unit|u]] (<sup>46</sup>Mn) to 65 u (<sup>65</sup>Mn). The primary [[decay mode]] before the most abundant stable isotope, <sup>55</sup>Mn, is [[electron capture]] and the primary mode after is [[beta decay]]. == Precautions == Manganese compounds are less toxic than those of other widespread metals such as [[nickel]] and [[copper]]<ref>[http://www.minormetals.com/content/html/minormetals/about/AboutManganese.htm Manganese Technical Data]</ref>. Exposure to manganese dusts and fumes should not exceed the ceiling value of 5 mg/m<sup>3</sup><ref>[http://www.environmentwriter.org/resources/backissues/chemicals/manganese.htm Manganese Chemical Background]</ref> even for short periods because of its toxicity level. Manganese poses a particular risk for children due to its propensity to bind to CH-7 receptors. Manganese poisoning has been linked to impaired motor skills and cognitive disorders.<ref>{{cite web| url=http://rais.ornl.gov/tox/profiles/mn.shtml | publisher=Oak Ridge National Laboratory | title=Risk Assessment Information System Toxicity Summary for MANGANESE | access-date=2008-04-23}}</ref> Acidic permanganate solutions will oxidize any organic material they come into contact with. The oxidation process can generate enough heat to ignite some organic substances. In 2005, a study suggested a possible link between manganese inhalation and central nervous system toxicity in rats. <ref>{{cite web|title=Elsevier Article Locator|url=http://dx.doi.org/10.1016/j.mehy.2005.01.043}} 080225 dx.doi.org</ref> It is hypothesized that long-term exposure to the naturally occurring manganese in shower water puts up to 8.7 million Americans at risk. A form of neurodegeneration similar to [[Parkinson's Disease]] called "[[manganism]]" has been linked to manganese exposure amongst miners and smelters since the early 19th Century. Allegations of inhalation-induced manganism have been made regarding the welding industry. Manganese exposure [[USA]] is regulated by [[Occupational Safety and Health Administration]]. <ref>{{cite web|title=Safety and Health Topics: Manganese Compounds (as Mn)|url=http://www.osha.gov/dts/chemicalsampling/data/CH_250190.html}} 080225 osha.gov</ref> == See also == *[[Parkerize]] *[[Potassium permanganate]] *[[Magnet]] *[[Chemical element]] *[[Periodic table]] *[[Manganism]] ==References== <references/> *[http://periodic.lanl.gov/elements/25.html Los Alamos National Laboratory &ndash; Manganese] == External links == {{Commons|Manganese}} {{wiktionary|manganese}} *[http://www.npi.gov.au/database/substance-info/profiles/52.html National Pollutant Inventory - Manganese and compounds Fact Sheet] *[http://www.webelements.com/webelements/elements/text/Mn/index.html WebElements.com &ndash; Manganese] *[http://www.manganese.org International Manganese Institute] *[http://dx.doi.org/10.1016/j.mehy.2005.01.043 Neurotoxicity of inhaled manganese: Public health danger in the shower?] *[http://www.cdc.gov/niosh/topics/manganese/ NIOSH Manganese Topic Page] {{clear}} {{Compact periodic table}} [[Category:Chemical elements]] [[Category:Dietary minerals]] [[Category:Transition metals]] [[Category:Manganese]] [[Category:Deoxidizers]] [[Category:Occupational safety and health]] <!-- interwiki --> [[af:Mangaan]] [[ar:منغنيز]] [[az:Manqan]] [[bn:ম্যাঙ্গানিজ]] [[be:Марганец]] [[bs:Mangan]] [[bg:Манган]] [[ca:Manganès]] [[cv:Марганец]] [[cs:Mangan]] [[co:Manganese]] [[cy:Manganîs]] [[da:Mangan]] [[de:Mangan]] [[et:Mangaan]] [[el:Μαγγάνιο]] [[es:Manganeso]] [[eo:Mangano]] [[eu:Manganeso]] [[fa:منگنز]] [[fr:Manganèse]] [[fur:Manganês]] [[gv:Manganaish]] [[gl:Manganeso]] [[ko:망가니즈]] [[hy:Մանգան]] [[hi:मंगनीज]] [[hr:Mangan]] [[io:Mangano]] [[id:Mangan]] [[is:Mangan]] [[it:Manganese]] [[he:מנגן]] [[jv:Mangan]] [[kn:ಮ್ಯಾಂಗನೀಸ್]] [[sw:Manganisi]] [[ht:Manganèz]] [[ku:Manganez]] [[la:Manganum]] [[lv:Mangāns]] [[lb:Mangan]] [[lt:Manganas]] [[jbo:jinmrmanga]] [[hu:Mangán]] [[mk:Манган]] [[ml:മാംഗനീസ്]] [[nl:Mangaan]] [[ja:マンガン]] [[no:Mangan]] [[nn:Mangan]] [[oc:Manganès]] [[uz:Marganets]] [[nds:Mangan]] [[pl:Mangan]] [[pt:Manganês]] [[ro:Mangan]] [[qu:Manganisu]] [[ru:Марганец]] [[scn:Manganesi]] [[simple:Manganese]] [[sk:Mangán]] [[sl:Mangan]] [[sr:Манган]] [[sh:Mangan]] [[fi:Mangaani]] [[sv:Mangan]] [[ta:மாங்கனீசு]] [[th:แมงกานีส]] [[vi:Mangan]] [[tr:Mangan]] [[uk:Манган (елемент)]] [[zh:锰]]