chemical element symbol atomic number soft white metallic element metal group atomic mass highly properties similar metals including rapid air earth natural comprises stable slightly radioactive half life billion years times longer estimated age universe german robert discovered newly developed technique flame compounds chemical electronic applications metal easily convenient absorption range making frequent target laser manipulation known nutrient living organisms charge potassium actively taken treated animal cells similar ways characteristics soft white metal second non radioactive metals temperature similar metals metal violently water potassium slightly slightly reaction usually vigorous hydrogen gas produces reported spontaneously air forms mercury gold iron potassium group low energy potassium similar purple color flame test distinguishing elements requires sophisticated compounds probably compound induce living cells dna nature found small quantities living organisms present replaces potassium common compounds starting material based chemical processes optical glasses copper silver highest room temperature known crystal property exploited thin film batteries applications forms number exposed air including excess oxygen gives forms producing earth crust composed stable radioactive natural radioactive specific activity significantly expose photographic film days additional synthesized half lives months highly radioactive uses half life years times age universe years making readily potassium minerals fairly widespread extensively dating rocks beta stable tends concentrate leaving liquid phase ratio increase time progressing results rocks elevated highest occur initial known age determined measurement concentrations ratio dates indicate true age minerals rocks subsequently altered dating element non natural produced electron capture decay half life days half life seconds stable occurrence abundant element earth crust roughly abundant common copper occurs naturally minerals contain contains commercial source element potassium minerals potassium contain element commercially significant quantities contains average compared higher value potassium lower value large radius incompatible elements concentrated heavier liquid phase largest deposits zone ore bodies formed process potassium far effective zone ore bodies containing quantities minerals source product notable sources rich deposits lake canada found italian island content deposits sources production abundant earth crust limited applications lack mineral rich limits production compounds tonnes year methods available separating potassium yields subsequent steps pure methods reported process process years 1950s 1960s product potassium production called main source contained rest potassium small today largest producers canada produce product history discovered robert germany mineral bright red lines spectrum chose derived latin word meaning deep red minor component processed containing potassium form acid slight difference hot water obtained reduction hydrogen process yielded grams studies began large scale isolation compounds litres gal mineral water yielded grams grams second element shortly discovered year invention scientists estimate atomic weight new element currently accepted value tried generate instead metal obtained blue substance naked eye microscope showed trace metallic substance presumed product probably mixture metal second attempt produce metallic able reduce heating able determine density melting point quality research 1860s fact determined density differs melting point presently accepted values slight discovered theory established low level activity half life greater years interpretation complicated proven decay stable beta decay discussion late 1940s minimal industrial value 1920s important use research development primarily chemical electronic applications produce won nobel prize physics applications compounds fireworks purple color considered use generator principle formed heat high temperature passed magnetic field conduct electricity act like generator generating electric current particularly commonly atomic species employed laser cooling desirable features application include ready availability inexpensive laser light relevant moderate temperatures required obtain substantial pressures producing volumes gas nuclear spins aligned random pumped laser interaction spin cells useful measurements producing beams purposes element atomic utilizes structure energy levels useful high precision timing main component secondary frequency references cell site electronic networking test equipment standards gps produce primary frequency standard greater accuracy expensive standards standards mass produced industry potential current uses include working fluid turbines vacuum tubes component ingredient special types glass production burning oxygen study potassium channels biology atomic particular metals development spin exchange free similar potassium tissue high potassium content accumulate radioactive main uses imaging result changes blood brain barrier brain collects brain normal brain tissue allowing use nuclear medicine locate image brain short half life seconds production decay close patient tested influence depression depression patients suffering depression help depression tests administered day days precautions biological effects violently water cause fires ensure safety purity metal usually kept dry mineral oil sealed glass atmosphere forms exposure small air oil storage subject similar precautions storage metallic potassium like potassium state dissolved water biological contexts human body tends treat potassium body fluid inside cells particularly toxic person contains average increase value times negative effects test persons biological half life humans measures days partial potassium possible potassium muscle tissue rats replaced rats died


chemical element symbol atomic number extremely radioactive synthetic element element created laboratory found nature stable known half life minutes created centre heavy research near germany named physicist spelled periodic table block element member 7th period placed group elements chemical experiments carried confirm heavier gold group calculated similar properties lighter copper silver gold differences history official discovery synthesized international team led germany december team bombarded target accelerated detected single reaction previously conducted joint institute nuclear research soviet_union observed joint working party concluded insufficient evidence discovery time team repeated experiment detected report decided team acknowledged discovery element naming nomenclature unnamed elements known gold published recommendations according element called corresponding symbol systematic element element discovered discovery confirmed permanent decided widely chemical community levels chemistry classrooms advanced textbooks recommendations ignored scientists field called element symbol simply suggested team honor german physicist rays accepted november stable naturally occurring radioactive synthesized laboratory fusion lighter elements intermediate decay products heavier elements seven different reported atomic masses known unconfirmed states decay alpha decay spontaneous stability half lives extremely unstable radioactive general heavier stable lighter stable known heaviest known half life minutes reported half lives second remaining half lives range predicted stable beta decay known observed undergo beta decay unknown expected long half lives second minutes respectively discovery predicted long half lives second minute minutes respectively discovered shorter half lives seconds minutes respectively predicted properties chemical ninth member series transition metals element shown transition metal expected elements form fourth transition metal series calculations atomic similar lighter gold implying basic properties resemble group elements copper silver gold predicted differences lighter predicted noble metal based stable states lighter group elements predicted stable states stable state state predicted stable iii expected comparable gold iii stable form larger variety compounds gold forms somewhat stable state effects electron affinity expected significantly lower gold value stable possible effects spin orbit interactions near end fourth transition metal series making higher states like stable lighter gold mercury known compound participate bonding greater extent spin orbit interactions stabilize molecular compounds bonding example expected stable expected stable expected difficult obtain probable chemistry received interest previous elements group elements expected contracted strongly calculations molecular compound effects double strength hydrogen bond spin orbit interactions weaken compounds studied predicted metal softer disagreement behave acid base solution form bond distance expected form complexes hydrogen physical atomic expected solid normal conditions body centered cubic structure unlike lighter face centered cubic structure expected different electron charge heavy metal density comparison known element density measured density results high atomic weight effects production measure quantity impractical sample quickly decay stable group elements copper silver gold outer electron configuration elements excited state configuration spin orbit state split pair energy levels copper difference energy ground state lowest excited state causes metal appear reddish silver energy gap widens atomic number increases excited levels stabilized effects gold energy gap decreases appears gold calculations indicate level stabilized extent ground state level excited state resulting energy difference new ground state excited state similar silver expected appearance atomic radius expected experimental chemistry determination chemical characteristics established low yields reactions produce chemical studies carried produced half life second rate production week half life stable known seconds long perform chemical studies obstacle need increase rate production allow experiments carry weeks months significant results obtained separation detection carried continuously separate automated systems experiment gas phase solution chemistry yields heavier elements predicted smaller lighter elements experimental chemistry received attention heavier elements despite early interest theoretical predictions effects group occurring


chemical element symbol atomic number gray transition metal resembles found minerals existence predicted identified making penultimate stable element discovered identified years later named latin copenhagen discovered processes use integrated circuits smaller feature lengths special applications contain combination large capture cross section makes good material absorption control rods nuclear power plants time requires removed transparent resistant nuclear characteristics physical characteristics shiny metal resistant similar having number group effects physical properties metal samples markedly affected especially nuclear properties elements difficult separate chemical similarity notable physical difference metals density having half density notable nuclear properties high thermal capture cross section different readily absorb apiece contrast practically transparent thermal commonly metal components nuclear especially nuclear fuel rods chemical characteristics air form protective film metal readily attacked burnt air like sister metal finely divided spontaneously air producing effect similar obtained dragon breath metal resistant concentrated chemistry similar separated basis differing chemical reactions melting points boiling points compounds major differences chemistry twin elements observed ranging mass number stable range radioactive half lives range years stable nuclear center controversy years potential use weapon occurrence estimated earth upper crust mass exist free element nature found combined solid solution natural compounds usually replaced rarely ratio increases mineral atomic old obsolete variety containing unusually high content major source heavy mineral sands ore deposits particularly brazil particularly crown deposit mount western_australia potential source containing rare new_south_wales australia reserves estimated years source world population increases demand grows reality occurs extraction extent low demand requires production heavy mineral sands ore deposits yield mined good nuclear fuel rod metal desirable properties low capture cross section good chemical stability high temperatures absorbing properties cause far useful nuclear applications nearly complete separation necessary use nuclear power production free main source chemical properties nearly identical makes difficult separate methods proven suitable industrial scale production chosen material nuclear programs 1940s separation method developed liquid liquid extraction processes wide variety developed production half metal manufactured produced product end product separation converted metal reduction process effected chemical transport reaction developed boer closed vessel temperatures forming reverse reaction happens set free forms solid coating react additional resulting steady turn chemical compounds form nearly identical series chemical compounds tends form compounds state react form higher temperatures oxygen nitrogen carbon elements sixth period nearly identical radius applications production metal volatile structures compounds white melting point boiling point roughly similar slightly basic compound known melting point known metal melting point led proposals useful construction materials subjected high temperatures mixed possesses highest melting point currently known compound recent suggest melting point history report periodic law chemical elements predicted existence heavier analog time believed elements ordered atomic masses placed element spot exact placement elements location missing elements determining specific weight elements comparing chemical physical properties ray henry showed direct line effective nuclear charge led nuclear charge atomic number element place periodic table method determined number showed gaps atomic number sequence numbers discovery gaps led extensive search missing elements people claimed discovery henry predicted gap periodic table element asserted found element rare earth elements published results chemical behavior matched element found later claim turned long standing controversy controversy partly favored chemical techniques led discovery relied use new ray method proved substances discovered contain element early charles bury suggested element resemble rare earth elements group suggestions based theories ray chemical arguments friedrich encouraged suggestions claims element rare earth element discovered von motivated search new element discovered copenhagen denmark original prediction ultimately found norway ray analysis place discovery took place led element named latin copenhagen home town today faculty science university copenhagen uses seal stylized image separated repeated double potassium von van jan boer prepare metallic passing heated process differential use today predicted elements missing periodic table radioactive elements present trace amounts environment making elements unknown non radioactive elements discovered element stable discovered applications details contribute fact technical uses close similarity makes possible use applications second available pure metal use nuclear industry free late 1950s furthermore low abundance difficult separation techniques necessary scarce produced production control rods nuclear nuclear absorb multiple makes good material use control rods nuclear capture cross section times elements good control rods excellent mechanical properties exceptional resistance properties allow use harsh environment water german research uses common military naval seldom found civilian ones core atomic power station conversion naval notable exception iron metals liquid rocket example main engine apollo lunar consists small additions increase adherence protective scales based improves resistance especially temperature conditions tend break scales inducing thermal stresses bulk material layer based compounds employed gate generation integrated circuits based compounds practical high allowing reduction gate current improves performance scales utilized applications evolution earth mantle time half life approximately billion years materials dominant host focus studies geology readily substituted crystal resistant mobility contamination extremely low ratio making correction initial minimal system model age time derived given reservoir depleted mantle ages carry significance techniques results yield provide average age material derived mineral contains amounts act given high variable found useful dating events uses heat resistance affinity oxygen nitrogen good oxygen nitrogen gas filled lamps cutting ability shed air high energy content concern funded program program determined possibility nuclear mentioned construct high yield weapons ray triggering mechanisms application induced gamma expense controversy precautions care needs taken fine particles spontaneously exposed air compounds contain metal rarely encountered people pure metal considered toxic compounds handled toxic forms metals normally greatest risk limited animal testing compounds people exposed workplace breathing skin contact eye contact safety health administration set legal limit exposure limit exposure compounds workplace hour national institute safety health set recommended exposure limit levels immediately dangerous life health


chemical element symbol atomic number rare transition metal belonging platinum group periodic table like metals platinum group chemicals baltic german scientist discovered element named homeland russian_empire russia latin names usually found minor component platinum annual production tonnes produced wear resistant electrical contacts thick film minor application platinum chemistry catalyst characteristics physical properties hard white metal member platinum group group periodic table group elements shell shell electron final electron lower shell observed neighboring metals crystal modifications subject high temperatures fused attacked regia attacked high temperatures readily attacked agents small amounts increase platinum resistance increased markedly addition small metal thermal known temperatures transition metals assume group state stable heavier group left table second row transition metals display notable differences chemical behavior like iron unlike form lower states downward trend melting boiling points transition metals maximum seen half contributing metallic bonding previous element exceptionally low value trend half filled configuration small energy needed configuration indicates far trend series transition series unlike lighter iron room temperature iron point reduction acidic solution common shown naturally occurring composed seven stable additionally radioactive discovered stable half life days half life days half life days characterized atomic weights ranging half lives minutes half life hours half life hours primary decay mode abundant electron capture primary mode beta primary decay product primary decay product occurrence abundant element earth crust relatively rare found parts element generally found platinum group metals mountains north south_america small commercially important quantities found extracted ontario canada deposits south_africa native form rare mineral replaces structure production mining roughly tonnes mined year world reserves estimated tonnes composition mined platinum group metal varies widely depending formation example mined south_africa contain average mined ussr contain considered minor platinum group metals like platinum group metals obtained commercially product copper platinum metals ore processing copper noble metals silver gold platinum group metals mud extraction metals converted methods depending composition representative method fusion followed dissolution regia solution mixture acid regia readily leaving metals solution separated treatment containing treated producing dissolved volatile separated precipitation extraction organic volatile hydrogen reduce yielding powder method similar procedure william methods suitable industrial scale production case product reduced hydrogen yielding metal powder metal treated powder techniques arc nuclear products contain significant amounts lighter platinum group metals spent nuclear fuel potential source extraction expensive radioactive require spent fuel stored multiple half lives factors far discouraged large scale extraction started chemical compounds states range properties compounds similar states common prevalent precursor red solid poorly defined versatile state turn volatile yellow aggressive strong agent structure properties analogous like potent stain electron organic materials reveal structure samples potassium known unlike stable strong agent acid organic like room temperature easily reduced solutions form dioxide unlike iron like form lower states forms reacted directly structure contain like iron readily form prefers achieve high coordination numbers instead reduced cold potassium form black potassium state potassium produced potassium gas unstable reduced water form orange potassium synthesized reacting metal potassium potassium mixed known highest known dark brown solid violently contact water easily form mixture lower releasing gas dark green solid readily melting yellow probably formed reducing compounds high states known known compound existing black form dark brown form red known dark brown dark brown black known brown black blue known pale green coordination complexes forms variety coordination complexes examples derivatives exist iii derivatives numerous best known forms wide range compounds carbon bonds catalyst analogous structurally exhibits distinctive properties liquid converts absence pressure dark red solid carbon derivatives including complex heating solutions gives converts complex history naturally occurring platinum containing platinum group metals long time pre americans known material european century century platinum identified pure element natural platinum contained discovered decade 19th century platinum sands russian rivers gave access raw material use plates medals coins starting platinum production available russian_empire research eastern_europe possible polish chemist isolated element called discovered shortly south american platinum published announcement discovery work confirmed later withdrew claim discovery nearly discovered examined left crude platinum mountains regia find unusual metals thought found new metals called led long standing controversy composition able repeat isolation eventually relinquished claims chosen analysed samples stemmed mountains russia derives latin word historical area included present day western russia ukraine parts slovakia poland russian scientist baltic german descent showed compounds prepared contained small amounts discovered year isolated platinum production working university way heavier discovered decades earlier showed contained new metal obtained grams crude platinum regia choosing new element stated named new body honour right relinquished word exist chemistry applications platinum electrical contacts thin film sufficient achieve desired similar properties lower cost electric contacts major use plate applied base dioxide lead thick film chip electronic applications account consumption seldom metals outside platinum group small quantities improve properties added resistance led development special advanced high temperature single crystal applications include turbines jet engines based compositions described containing fountain pen frequently tipped onward famous parker fountain pen fitted gold tipped component mixed metal protection underground submerged structures cells processes generating salt water complexes oxygen finding use sensors oxygen red biological stain stain molecules light electron beta decaying eye mainly centered complexes researched possible properties compared platinum complexes greater resistance selective action drugs undergoing clinical evaluation treatment reacting contact producing brown black dioxide pigment versatile catalyst suspension cds particles loaded dioxide energy visible light split hydrogen process day remove oil industrial processing facilities complexes found highly efficient process important applications organic chemistry promoted fischer synthesis solar energy conversion complexes absorb light visible spectrum actively researched solar energy technologies example based compounds light absorption solar cells promising new low cost solar cell system data storage chemical deposition produce thin films pure films promise use giant read element hard disk drives suggested compatible processing techniques exotic materials based unusual properties quantum critical point behavior exotic high temperature


known simply element hypothetical chemical element atomic number symbol temporary systematic symbol permanent decided periodic table elements expected block element metal element eighth period element lowest atomic number synthesized multiple attempts american german russian teams element unsuccessful experimental evidence shown synthesis likely far difficult previous elements penultimate element synthesized current technology position seventh metal suggests similar properties lighter potassium effects cause properties differ expected straight application periodic trends example expected closer behavior potassium characteristic state metals predicted state unknown metal history elements produced nuclear fusion fusion reactions divided hot cold fusion depending energy compound nucleus produced hot fusion reactions light high energy projectiles accelerated heavy targets giving rise compound high energy alternatively cold fusion reactions use heavier projectiles typically fourth period lighter targets usually lead fused produced relatively low energy decreases probability products undergo reactions fused cool ground state require hot fusion reactions tend produce rich products highest elements presently quantities elements elements synthesized attempts push limits current technology decreasing cross sections production reactions probably short half lives expected order heavier elements likely short lived detected current technology decay reaching previously important help characterized silver bullets synthesis elements came deformed nuclear shells increased stability surrounding existence quasi stable rich produce rich elements rich closer expected sought island stability synthesized fewer expected island stability furthermore require target difficult produce sufficiently large quantities practical production elements require projectiles heavier synthesis attempts synthesis attempted bombarding target berkeley california identified leading limiting cross section later calculations suggest cross section reaction result products actually thousand times lower upper bound element target synthesis experiments german russian teams recent years russian experiments conducted results released strongly implying identified april september attempt bombarding target centre heavy research germany based theoretically predicted cross section expected synthesized months beginning experiment experiment originally planned continue november stopped early use target confirm synthesis changing projectiles reaction predicted favorable practical reaction formation somewhat cold reaction superior preparing quantities target difficult necessary change silver bullet divides expected yield yield strongly dependent fusion reaction predicted short half lives team new fast electronics capable registering decay events identified implying limiting cross section predicted actual cross section limits current technology naming nomenclature unnamed elements known recommendations element temporarily called symbol discovered discovery confirmed permanent chosen widely chemical community levels chemistry classrooms advanced textbooks recommendations ignored scientists work theoretically elements element symbol predicted properties nuclear stability stability decreases greatly increase atomic number element half life orders magnitude longer currently known higher numbered element atomic number undergo radioactive decay half lives hours elements atomic numbers lead stable reasons understood slight increase nuclear stability atomic numbers leads appearance known nuclear physics island stability concept proposed university california professor explains elements longer predicted alpha decay half lives predicted order longest alpha decay half life predicted decay modes predicted half lives drop tens consequences synthesis half lives decay reaching new theoretical models expected gap energy filled element filled element smaller expected element longer appears stable spherical closed nuclear shell energy gap increase stability elements magic nucleus expected spherical element expected low half life low production cross section makes synthesis challenging atomic physical period element predicted metal potassium elements electron electron configuration easily lost chemical reactions form state metals elements predicted continue trend electron configuration expected behave like lighter predicted differ lighter metals properties main reason predicted differences metals spin orbit interaction mutual interaction motion spin interaction especially strong elements faster comparable speed light lighter electron energy levels corresponding electron energy levels stabilized effect called splitting splits stabilized stabilized parts understand split change second quantum number stabilized stabilized parts respectively outer electron stabilized harder remove expected allowing participate chemical reactions significant key factor affecting chemistry causes trends atomic molecular properties metals reverse direction outer electron energy energy required remove electron neutral predicted higher known metals potassium onward effect large element predicted lower energy metal period lowest energy period true previous periods electron affinity expected far greater expected electron affinity higher metals lighter effects cause large drop static quantity impacts proportional square element atomic number calculated small similar electron hydrogen like electron predicted quickly mass times non moving electron feature coming effects comparison figure hydrogen like figure hydrogen like according simple laws indirectly indicates atomic radius close metallic radius lowered radius expected predicted melting point liquid room temperature known continues trend decreasing melting points group melting point known poorly having variously stated values close value possibly extreme heat generated radioactive decay boiling point expected lower previous elements group following downward periodic trend density variously predicted continuing trend increasing density group predicted value chemical chemistry predicted similar metals probably behave like potassium unusual periodic trends ignoring effects predict lowered electron increasing energy decreasing metallic effect seen chemistry state similar chemistry hand radius predicted larger larger lower shells state seen metal addition state characteristic metals main state known metals expansion causing lower energy expected compounds expected large character involvement bonding effect seen lesser extent shows contribution bonding instead element simple indicate instead retains position likely close scale gas phase low temperatures condensed phase metals form molecules metal metal bond lengths molecules increase group decrease aforementioned effects stabilize opposite trend shown metal metal bond energies bond slightly stronger bond energies predicted value bond weakest bonds gold metal stable gives medium sized gold value platinum silver smallest metals demonstrate feasible study surfaces noble metals surface predicted lowest metals information useful future chemistry experiments values related metals change opposite directions atomic number increases


chemical element symbol atomic number produced entirely cosmic ray stellar low abundance element solar system earth crust concentrated earth water common naturally occurring compounds minerals mined largest known deposits turkey largest producer minerals found small amounts found naturally earth pure produced difficulty contamination carbon elements exist brown powder black extremely hard scale poor electrical conductor room temperature primary use applications similar carbon fibers high strength materials primarily chemical compounds half consumption globally glass fibers containing structural materials leading use high strength lightweight structural materials glass desired greater strength thermal shock resistance ordinary lime glass compounds agriculture small reagent synthesis organic fine chemicals containing organic study natural composed stable number uses capturing agent biology low mammals similar table salt toxic acid mildly natural containing organic known essential life small amounts compounds play strengthening role cell walls plants making necessary plant nutrient involved calcium plants animals considered essential nutrient humans implicated history word coined mineral isolated analogy carbon resembles mineral form known china crude reached west persian ibn apparently mentioned polo brought italy 13th century reports use acid recognized hot springs near florence italy known primarily medical uses rare mineral called found italy main source european american sources replaced compounds relatively rarely late 1800s francis smith pacific_coast company popularized produced volume low cost recognized element isolated sir joseph louis gay louis observed electric current sent solution produced brown subsequent experiments potassium reduce acid instead produced confirm new element named element gay iron reduce acid high temperatures air showed acid product identified element pure arguably produced american chemist preparation laboratory earliest routes involved reduction metals aluminium product contaminated metals pure prepared reducing volatile hydrogen high temperatures use industry produced high temperatures zone melting processes production compounds involve formation exploits convenient availability characteristics similar carbon capability form stable molecular networks nominally contains regular randomly long range order hard black material melting point forms major phase exists difficult produce significant contamination phases based phase described type arrangement atomic pairs produced phases heating remains stable releasing temperature pressure phase produced similar pressures higher temperatures phases ambient conditions phase stable produces phase unknown structure phase temperatures like molecules proposed like structure described chemistry element rare poorly studied pure material extremely difficult prepare studies involve samples contain small amounts carbon chemical behavior resembles aluminium resistant attack boiling acid finely divided attacked slowly hot concentrated hydrogen hot concentrated acid hot acid hot mixture rate depends particle size purity temperature react air room temperature higher temperatures burns form undergoes example practice usually chemical compounds familiar compounds formal state iii include adopt structure compounds lewis readily form electron pair donors called lewis bases example combined industry catalyst react water form acid found nature earth entirely iii associated elements minerals contain state minerals resemble respect found coordination oxygen configuration unlike minerals contain coordination number greater typical motif exemplified common mineral shown left formal negative charge center balanced metal minerals chemical compounds hydrogen generic formula compounds occur nature readily contact air violently parent member called known state form larger consist clusters exist example based fusion clusters important products large number known formal number positive based assumption hydrogen counted active metal mean number simply ratio hydrogen example state compounds state number notable variety structures adopt exhibit structures analogous carbon including diamond diamond like structure called cubic exist structure diamond bonds viewed coordinate bond donated nitrogen acts lewis base bond lewis acidic iii centre cubic applications comparable diamond substances able produce compound positively charged negatively charged nitrogen plane lie adjacent charged plane consequently different properties planes slip past easily relatively poor electrical thermal conductor directions chemistry large number compounds known useful organic synthesis produced employs simple chemical iii compounds usually example multiple reacting tendency form novel sided sided structures composed completely varying numbers carbon chemicals employed uses diverse complex hard composed carbon cluster carbon cluster chemistry compounds form structures including acid example form useful molecular add considerable amounts order containing compounds capture therapy cancer compounds found earth naturally forms variety stable compounds formal state compounds formal states little meaning metal form derivatives isolated condensed form characterized metal compounds metal contain negative states formal charge assigned formal charge material centers extra double bond forming sheets akin carbon unlike lacks plane allow conduct electricity similar material found high temperature certain metal find specialized applications hard materials cutting tools states calcium structural perspective distinctive chemical compounds included series cluster compounds compounds contain coordination numbers greater naturally occurring stable mass difference results wide range values defined difference traditionally expressed parts thousand natural waters ranging known shortest lived alpha decay half life controlled exchange reactions species mineral phase changes systems alteration rock effect results removal results solutions enriched responsible large relative oceanic crust continental crust difference act signature exotic exhibits nuclear halo radius larger predicted liquid drop model useful capturing thermal cross section typical cross sections nuclear industry natural nearly pure valuable product depleted nearly pure commercial high cross section control nuclear capturing substance industrial scale processes developed vacuum column enriched enriched radiation primary capture therapy cancer capture therapy compound containing incorporated taken tissues near patient treated beam low energy relatively low radiation dose trigger energetic short range secondary alpha particle heavy radiation products nuclear reaction radiation additionally especially inside cells nuclear control emergency systems serve function form control rods acid water acid added plant shut slowly filtered months material fuel future manned spacecraft theoretical role structural material fibers material serve special role radiation shield difficulties dealing cosmic rays high energy secondary radiation interaction cosmic rays spacecraft materials high energy materials high light elements continue radiation hazard actively absorbed light elements absorb thermal appear potential spacecraft structural materials serve mechanical reinforcement radiation protection depleted radiation hardened cosmic radiation produce secondary hits spacecraft structures captured present spacecraft producing gamma ray alpha particle resultant decay products nearby chip structures causing data loss bit single event upset radiation hardened designs use depleted greatly enriched contains useful largely immune radiation damage depleted nuclear industry fusion candidate fuel fusion struck energy produces alpha particles energy fusion reactions involving hydrogen produce penetrating radiation structures long term operating personnel alpha particles fusion turned directly electric power radiation stops soon turned possess nuclear spin nuclear spin use nuclear magnetic resonance specially adapted detecting available commercially cause splitting attached occurrence rare universe solar system trace formation big bang stars formed minor amounts cosmic ray found cosmic dust materials high oxygen environment earth found fully appear earth form extremely tiny detected lunar relatively rare element earth crust representing crust mass highly concentrated action water found naturally combined compounds acid found volcanic spring waters minerals known production economically important sources minerals constitute mined containing ore largest global deposits known central western turkey including provinces global proven mineral mining reserves exceed billion metric tonnes yearly production million tonnes turkey united_states largest producers products turkey produces half global yearly demand works turkish turkish state owned mining chemicals company focusing products holds government monopoly mining minerals turkey possesses world known deposits held share production global minerals ahead main competitor rio group quarter global production comes single rio known near california market trend average cost free chiefly making fibers deposited chemical deposition core fibers lightweight composite applications high strength tapes use small fraction total use introduced compounds estimated global consumption entirely compounds million tonnes mining capacities considered adequate meet expected levels growth decade form consumed changed recent years use like declined following concerns content consumers moved use refined acid lower content increasing demand acid led number producers invest additional capacity turkey state owned works opened new acid plant production capacity tonnes year rio group increased capacity plant tonnes year tonnes year plans grow tonnes year chinese producers unable meet rapidly growing demand high quality led imports growing acid imports increasing year period rise global demand driven high growth rates glass fiber production rapid increase manufacture reinforcement grade containing asia offset development free reinforcement grade europe usa recent rises energy prices lead greater use grade consequent growth consumption consulting group forecasts world demand grow year reach million tonnes highest growth demand expected asia demand rise average year applications nearly ore extracted earth destined acid united_states production glass major global industrial scale use compounds end use production glass fiber containing structural especially asia added glass influence strength qualities glass fibers global production glass high strength global including super hard materials discussed agriculture global production fiber fibers high strength lightweight materials chiefly advanced structures component composite materials limited production consumer sporting goods golf clubs fishing rods fibers produced chemical deposition fibers sub millimeter sized springs produced laser assisted chemical deposition translation focused laser beam allows produce complex structures structures good mechanical properties elastic fracture strain fracture stress applied reinforcement systems fiber reinforced plastic reinforced glass fibers commonly woven mat glass fibers material types glass depending use glasses contain varying amounts calcium present added increase strength glass agent decrease melting temperature high easily worked pure form glass fibers highly glasses glass named electrical use common general use glass glass mainly glass reinforced common high glasses include glass lime glass high content glass staple fibers glass glass named low constant contain global scale contain use construction containing consume half global production single largest commercial market glass glass typically low thermal expansion giving good resistance thermal shock major brand names glass laboratory consumer chiefly resistance compounds known extreme material obtained carbon electric structure approximately shows clear carbon suggested ratio complex structure substance seen formula motif carbon suggested units replaced chains smaller present article structural analysis repeating plus semi structure gives great structural strength weight tank armor numerous structural applications ability absorb forming long lived especially extra makes material attractive radiation arising nuclear power plants nuclear applications include control rods shut control rods increase surface area high compounds cubic widely material carbon similar carbon soft like cubic hard diamond like forms high temperature component known commercial superior slightly smaller chemical stability superior diamond called diamond like compound metal metal coating tools chemical deposition physical deposition metals beam deposition results spectacular increase surface resistance laser successfully purpose alternative diamond coated tools treated surfaces similar properties bulk example produced ambient pressures expensive exhibits considerable layered structure value comparable similarly possess high wear resistance bulk form components exposed high temperatures wear loads agents household laundry cleaning products including team laundry hand soap present tooth serves source active oxygen laundry cleaning products laundry despite laundry longer contains compounds instead agent acid notably ants useful having fewer electron host hole resulting type traditional method introducing atomic high temperatures process uses solid liquid sources 1970s replaced relies source gas important chemical industry metals injected deposition source examples deposition containing hard carbon films films diamond film component strongest type permanent found variety electronic devices magnetic resonance imaging medical imaging systems compact relatively small motors examples computer hard disk drives compact disk dvd digital versatile disk players rely motors deliver intense power remarkably compact package mobile phones neo provide magnetic field allows tiny speakers deliver audio power nuclear control nuclear taking advantage high cross section capture water variable concentration acid cooling water compensate variable fuel new rods inserted concentration acid reduced lifetime uses distinctive green flame based contain anti systems contain silver gold metals fire rubber articles acid known acid production textile flat panel displays based substance fuel whitney engines lockheed engines saturn rocket utilized nasa apollo programs suitable properties especially fact burns high temperature industrial radical reactions effective low temperatures environmentally wood biological applications acid properties reasons applied water swimming pool water treatment mild solutions acid eye marketed appears active element approved organic new class drug called active form currently experimental trials types site high affinity number potential prepared use capture therapy compounds promise treating generally approved purpose marketed treat fungus gained approval july research areas important material transition temperature wires produced powder tube process applied melting point forms thin layers enhance electron mobility devices forms structures high strength high chemical stability high thermal list desirable properties biological role needed life hypothesis suggested possible production mars life transported earth billion years ago exists known containing natural isolated essential plant nutrient required primarily maintaining integrity cell walls high soil concentrations greater lead marginal tip leaves poor overall growth performance levels low produce symptoms plants particularly sensitive soil nearly plants somewhat tolerant soil symptoms soil content greater content exceeds plants perform survive levels plant tissue exceed symptoms likely appear element necessary optimal health rats rats easy produce needed rats small amounts foods dust air required rats poor coat hair quality presumably necessary mammals syndrome humans described small amounts occur widely diet amounts needed diet extension studies small exact role animal kingdom poorly understood occurs foods produced plants value argued thought plays roles animals including humans united_states department agriculture conducted experiment women took day results showed supplemental reduced calcium activated suggesting possible role suppression effects conventionally medicinal determined national health states total daily intake normal human ranges day type rare form linked gene reportedly regulating concentration determination content food materials method converted acid reaction acidic solution red colored complex formed health issues acid compounds humans animals similar table salt dose mortality animals body weight substances considered minimum lethal dose humans established intake day acid reported incident considered toxic grams day days cause minor digestive problems suggestive single medical acid capture therapy fish survived min saturated acid solution survive longer strong solutions acid toxic insects mammals routinely hydrogen compounds similar compounds poisonous usual element poisonous depends structure toxic highly require special care handling presents fire hazard owing reducing nature liberation hydrogen contact acid


greek hidden chemical element symbol atomic number member group noble gases elements noble gas occurs trace amounts atmosphere rare gases lamps rare exceptions like noble gases lighting photography light lines useful bright high powered gas single line makes useful laser official length meter defined orange line high power relative ease operation discharge tubes history discovered britain sir william scottish chemist morris english chemist left nearly components liquid air neon discovered similar procedure workers weeks later william awarded nobel prize chemistry discovery series noble gases including international conference weights measures defined meter light emitted agreement replaced international prototype meter located paris metal bar platinum series standard meter bars originally constructed quadrant earth polar definition based red line replacing definition lasted october conference meter distance light travels vacuum characteristics characterized sharp lines signatures strongest green yellow products solid white face centered cubic crystal structure common property noble gases close packed crystal structure naturally occurring earth atmosphere composed stable addition thirty unstable known product atmospheric reactions produced naturally occurring radioactive half life years highly volatile stay solution near surface water dating old years radioactive noble gas half life years produced nuclear bomb testing nuclear released fuel rods nuclear concentrations north pole higher south pole convective mixing chemistry like noble gases highly fact 1960s noble gas compounds synthesized following successful synthesis compounds synthesis reported year reported subsequently shown mistaken identification extreme conditions form according following equation compounds discovered reports salt investigated evidence reaction produces unstable compound contains oxygen bond nitrogen bond found produced reaction reported stable crystals grown pressures face centered cubic structure surrounded randomly oriented hydrogen molecules natural occurrence earth retained noble gases present formation concentration atmosphere extracted liquid air space uncertain measurement derived activity solar winds measurements suggest abundance space applications multiple lines gas appear whitish turn makes based useful photography brilliant white light source photographic flashes high speed photography gas combined gases signs glow bright greenish yellow light mixed energy efficient lamps reducing power consumption reducing light output raising cost costs times fill lamps reduce allow higher operating temperatures brighter light results blue color conventional lamps white discharge good effect colored gas discharge tubes simply painted stained create desired color example neon type multi colored advertising signs entirely based produces higher light power neon red line region reason red high power laser light shows mirrors select red line laser familiar neon variety achieve multi laser important nuclear fusion energy research confinement experiments laser high beam short spot size varied track experimental particle physics liquid construct quasi electromagnetic notable example experiment containing tonnes liquid usage rare liquid expensive advantage smaller radius provides excellent spatial resolution little overlapping parameters relevant radiation length density sealed spark gap assemblies older jet engines contain small produce consistent levels uniform operation application magnetic resonance imaging imaging particular enables distinguish surfaces containing potential use assess regional ventilation properties limit fraction breathing gas breathing mixture comparable effectiveness fraction avoiding unwanted effects high partial pressure gas atmosphere detect clandestine nuclear fuel facilities north_korea pakistan facilities detected early 2000s believed producing weapons grade precautions considered non toxic seven times greater air breathing atmosphere natural air happen locality leak causes humans similar breathing air times atmospheric pressure comparable diving depth nitrogen affect breathing time mixture contain oxygen normal greater concern


chemical element symbol atomic number white metal slight golden belongs transition metals hard pure maximize surface area shows significant chemical activity larger pieces slow react air standard conditions layer forms surface prevents pure native found earth crust tiny amounts usually rocks interiors larger iron exposed oxygen outside earth atmosphere found combination iron reflection origin elements major end products iron mixture thought compose earth inner core use natural iron traced far bce isolated classified chemical element initially ore copper mineral element comes german mythology similar old nick fact copper resisted copper economically important source iron ore contains important ore minerals include major production sites include region canada thought origin new pacific russia slowly room temperature considered resistant historically plating iron brass coating chemistry equipment manufacturing certain retain high polish german silver world production resistant pure plating objects provoke widely coins rising price led replacement cheaper metals recent years elements room temperature permanent based partly intermediate strength iron based permanent rare earth metal valuable modern times chiefly world production particularly steel common new comprise remainder world use chemical uses compounds consuming production compound number niche chemical manufacturing uses catalyst essential nutrient plants active site properties atomic physical properties white metal slight golden takes high polish elements magnetic near room temperature iron temperature meaning bulk non magnetic temperature unit cell face centered cube giving atomic radius crystal structure stable pressures belongs transition metals hard electron configuration dispute electron configurations close energy symbol refers like core structure disagreement configuration lowest energy chemistry textbooks quote electron configuration written configuration agrees energy ordering rule filled supported experimental fact lowest energy state energy level specifically level configurations gives rise energy levels sets energy levels overlap average energy states configuration actually lower average energy states configuration reason research literature atomic calculations quotes ground state configuration range atomic weight naturally occurring composed stable abundant natural abundance heavier formed nuclear fusion losing energy highest nuclear binding energy binding energy greater incorrectly cited tightly bound tightly bound stable daughter product extinct half life million years long half life persistence materials solar system generate variations composition abundance present extraterrestrial material provide insight origin solar system early history characterised stable half life years years days remaining radioactive half lives hours majority half lives seconds element state radioactive produced burning process later set free large quantities type shape light curve intermediate late times corresponds decay electron capture ultimately long lived half life years found applications geology date terrestrial age determine extraterrestrial dust ice sediment half life recently measured believed important elements heavier iron discovered rich heavy element known double magic like unusually stable occurrence earth occurs combination iron mineral commonly found iron bulk mined types ore deposits principal ore minerals second deposits principal ore mineral australia new biggest estimate reserves identified land based resources world averaging greater comprise million tons double known reserves deposits evidence earth believed earth outer inner naturally occurring iron usually proportion carbon present content found iron compounds common state compounds known exotic states produced studied discovered volatile highly toxic liquid room temperature heating complex carbon behavior exploited process described related complex useful catalyst easily displaced complexes uncommon example complex complexes feature bonding dark red prepared reduction compound water thought state important containing reduction forms compounds common including produced large quantities metal acid forming useful common dissolve water green solutions metal complex form compounds molecules feature centres common behavior produced acid usually encountered green formula usually written dissolved water salt forms metal complex gives yellow complexes exist square complexes square complexes having properties magnetic formation complexes contrast complexes heavier group metals platinum form square geometry known electron count making relatively unstable iii numerous iii compounds known examples iii iii forms simple iii stabilized donor present mixed iii present iii batteries including iron hydrogen metal certain manufacturers batteries remains rare state compounds known date history easily mistaken silver understanding metal use dates relatively recent times use ancient traced far bce syria found contain ancient chinese manuscripts suggest white copper known bce white copper exported britain early 17th century content discovered medieval germany red mineral found ore mountains resembled copper ore miners unable extract copper blamed german mythology similar old nick copper called ore german copper ore known aka baron tried extract copper swedish village los instead produced white metal named spirit given mineral modern german originally source rare beginning obtained blue production large scale began norway rich introduction steel production increased demand deposits new discovered provided world supply discovery large deposits basin canada russia reef south_africa large scale production possible component coins mid-19th century birmingham forged coins trading malaya united_states term nick originally applied copper flying eagle cent replaced copper indian head cent later term designated cent increased cent shield copper appropriated designation proportion term present united_states coins nearly pure switzerland cent coins struck canada world largest producer time non war years metal content coins magnetic wartime period removed canadian coins save strategic armor canada higher value coins 21st century high price led replacement metal coins world coins include euro coins coins coins coins replaced steel began causing problems people public controversy world production philippines indonesia russia canada australia world largest producers reported geological survey largest deposits non russian europe located finland greece identified land based resources averaging greater contain million tons deposits addition extensive deep sea resources covering large areas ocean floor particularly pacific_ocean locality united_states mined oregon square miles bearing surface deposits located closed eagle project new michigan upper peninsula construction completed operations began quarter year operation eagle produced tonnes extraction obtained extracted ore conventional reduction processes yield metal greater purity steel applications pure depending traditionally processed techniques produce recent advances techniques resulted significantly metallic product deposits traditionally processed concentration process followed extraction processes concentrated differential ratio low processed gordon process copper removed adding hydrogen leaving concentrate extraction separate final content greater second common process metal salt solution followed electro winning solution plating process metal obtained process purity greater process patented industrial use beginning 20th century process reacted carbon presence catalyst form iron gives iron reaction slow necessary separated formed product reaction temperature non volatile solid obtained processes passed large chamber high temperatures tens thousands spheres called constantly stirred deposits pure spheres alternate process smaller chamber create fine powder carbon reused highly pure product known metal value market price early months april metal trading price subsequently fell dramatically september metal trading coin contains april price worth cents grams copper worth cents total metal value cents face value cents attractive target melting people wanting sell metals profit united_states mint anticipation practice implemented new interim rules december subject public comment days melting export cents punished fine imprisoned maximum years september melt value copper included face value applications global production presently follows steel uses specific recognizable industrial consumer products including steel batteries electric guitar strings microphone plating fixtures special plating green glass metal chief use cast varieties widely including copper aluminium lead silver gold resistant occasionally substitute decorative silver occasionally countries cheap metal later years 20th century replaced cheaper steel iron united_states canada excellent agent certain precious metals fire collector platinum group elements capable fully collecting elements partially collecting gold high mines engage recovery primarily platinum examples russia basin canada foam gas fuel cells frequently reactions finely divided aluminium common form related including type naturally material meaning presence magnetic field material undergoes small change length order negative indicating contracts cemented industry proportions weight makes magnetic adds resistance cemented parts biological role recognized 1970s plays important roles biology plants plant assists contains contain addition iron clusters present powers carbon consists cluster bearing include rare class bacteria parasitic parasites higher organisms including mammals contains implicated formation hard calcium plates tests sea affect human health dependent bacteria released traps volcanic site modern city suspected assisting growth genus produced biggest extinction event record major source exposure oral consumption found naturally food water increased human pollution example water soil mining dump waste water steel dishes release food atmosphere metal fossil fuel humans absorb directly tobacco smoke skin contact jewelry coins common form chronic exposure traces absorbed action average daily exposure pose threat human health absorbed day humans removed passed body eliminated tract absorbed cumulative poison larger chronic exposure toxic constitute hazard minimal risk level compounds set days dust believed compounds extremely toxic gas metal function metal carbon functional groups explosive air people exposed workplace contact skin eye safety health administration set legal limit exposure limit workplace hour excluding national institute safety health recommended exposure limit hour immediately dangerous life health upper limit day estimated average day large amounts comparable estimated average food cooked steel example cooking cycles serving sauce averages individuals skin contact known contact highly individuals react foods high content sensitivity present patients confirmed contact worldwide partly use jewelry pierced ears affecting pierced ears marked red skin low release address problem allowed products contact human skin regulated european_union researchers found released euro coins far excess standards believed result reaction voted year american contact society august american academy adopted position statement safety estimates suggest contact includes accounts approximately billion affects nearly million people reports induced activation factor regulation genes caused addition culture medium increased level reversed metal induced dependent gene expression


chemical element symbol atomic number rare white hard transition metal member platinum group naturally occurring naturally occurring usually found free metal similar metals rarely chemical compound minerals valuable precious metals noble metal resistant found platinum members platinum group metals discovered william ore named rose color compounds produced reacted powerful acid mixture regia element major use approximately world production way automobiles metal aggressive chemicals rarity usually platinum applied high temperature white gold thin layer improve appearance sterling silver resistance nuclear measure level history greek meaning rose discovered william soon discovery crude platinum ore presumably obtained south_america procedure involved ore regia acid precipitated platinum adding metals like copper lead precipitated acid dissolved dissolved regia precipitated addition washed rose red reacted displaced compound released free metal discovery rare element minor applications example turn century containing measure temperatures major application decorative uses resistant coating introduction way increased demand previous platinum way reduce exhaust characteristics hard metal high metal normally form heated oxygen absorbed atmosphere melting point released higher melting point lower density platinum attacked completely acid slightly regia chemical properties belongs group periodic table configuration shells group observed neighboring elements common state states observed unlike forms volatile oxygen compounds known stable include compounds known nearly range possible states iii examples lower states stable presence best known compound catalyst catalyst naturally occurring composed stable half life years half life days half life years half life days characterized atomic weights ranging half lives shorter hour hours hours numerous states stable half life years half life days weighing stable primary decay mode electron capture primary decay product greater primary decay mode beta primary product occurrence elements earth crust comprising estimated parts million rarity affects price use commercial applications mining price industrial extraction complex mixed metals silver platinum gold bearing minerals found platinum extracted white metal difficult fuse principal sources located south_africa river sands mountains north_america including copper mining area ontario region quantity small large processed ore makes recovery cost effective main south_africa approximately followed russia annual world production tonnes price highly variable cost approximately times gold times silver times copper weight price briefly rose kilogram economic 3rd quarter pushed prices sharply kilogram price rebounded early kilogram twice gold price late prices political financial problems led low oil prices causing metals drop price economies china india emerging countries slowed motor vehicles produced china excluding resulted price grams late november nuclear product kilogram product contains significant lighter platinum group metals including nuclear fuel potential source extraction complex expensive presence requires period cooling storage multiple half lives longest lived years factors source large scale extraction attempted applications primary use element automobiles changing harmful carbon nitrogen exhaust emissions gases consumed worldwide went recovered application glass industry production flat panel glass chemical industry catalyst world production consumed automobile platinum metals reduction nitrogen nitrogen oxygen number industrial processes notably produce acid process addition molecular double bonds process important manufacture certain reduce complex widely catalyst synthesis synthesis ornamental uses finds use jewelry decorations white gold platinum reflective white surface time sale thin layer wears away use known flashing jewelry business coating sterling silver protect silver produced atmospheric hydrogen solid pure jewelry rare difficulty high melting point poor high price high cost ensures applied honors elite status commonly metals silver gold platinum deemed insufficient book world records gave paul_mccartney disc history time best selling songwriter recording artist uses agent improving resistance platinum glass fiber production elements aircraft spark laboratory uses include electrical contacts valued small electrical resistance small stable contact resistance great resistance extremely hard useful optical instruments filters systems characteristic rays produces engineering nuclear measure levels method requires digital filter determine current level generating separate signals immediate seconds delay minute delay signal level combined signal nuclear vertical levels providing accurate picture allowing fine tuning consume nuclear fuel economically precautions noble metal pure chemical complexes median lethal dose rats kilogram body weight like noble metals occur chemical compounds nature found serve biological function form metal harmless people exposed workplace safety health administration specified legal limit exposure limit exposure workplace hour national institute safety health set recommended exposure limit level levels immediately dangerous life health compounds


chemical element symbol atomic number found free element nature found minerals combination iron metal important industrial metal uses particularly historically named black minerals region greece gave names similar sounding ore element iron century swedish chemist produce aware known dioxide contained new element unable sample metal reducing dioxide carbon prevention steel colors depend state earth metals powerful dioxide electron material carbon batteries biology function large variety functions particularly essential free organisms deal oxygen functions oxygen evolving complex plants element required trace mineral known living organisms larger amounts apparently far greater effectiveness cause poisoning mammals damage characteristics physical properties gray metal resembles iron hard difficult fuse easy metal common slowly air like iron water containing dissolved oxygen naturally occurring composed stable eighteen isolated described stable half life million years half life days half life days remaining radioactive half lives hours majority minute states iron group elements thought synthesized large stars shortly explosion half life million years relatively short half life relatively rare produced cosmic rays impact iron contents typically combined contents found application geology dating reinforce evidence early history solar system variations suggest initial ratio indicates composition result decay differentiated bodies provides additional evidence processes immediately solar system range atomic weight primary decay mode abundant stable electron capture primary mode beta decay chemical properties common states states observed competes biological systems compounds state restricted unstable compounds intensely purple powerful agents compounds states blue green strong agents vulnerable stable state pale pink color compounds known state seen mineral commonly exists high spin ground state high pairing energy examples low spin spin allowed transitions explaining compounds typically pale state known compounds like iii powerful agents prone solution forming solid compounds iii characterized strong purple red color preference distorted coordination resulting effect state produced dioxide produced compounds dioxide exposed air state compounds purple glass violet color potassium potent potassium called crystals commonly laboratory reagent properties medicine example treatment fish diseases solutions potassium preparation biological cells tissues electron history origin complex ancient times black minerals located modern greece called place origin thought differ gender male attracted iron iron ore known probably gave term female ore attract iron glass feminine later called known modern times dioxide mineral magnetic 16th century dioxide called note instead possibly corruption words eventually differentiate black ore white ore useful called finally metal isolated known german eventually refer white provided free element isolated later colorful example dioxide abundant nature stone age cave paintings years old contain compounds egyptian roman add remove color glass use soap continued middle ages modern times evident 14th century glass venice dioxide available experiments 17th century discovered dioxide converted useful laboratory reagent century swedish chemist dioxide produce acid mixture acid react dioxide later acid process dioxide recycled process production agents large consumer aware dioxide contained new element able sample metal reducing dioxide carbon content iron greece led steel produced ore contains additional making steel exceptionally hard beginning 19th century patents granted documented iron harder british academic james noted association miners heavy exposure form disease united_states patents granted protecting firearms conversion process seen widespread use invention cell subsequent improvement batteries containing dioxide increased demand dioxide development batteries batteries contained carbon battery battery normally use produced dioxide natural occurring dioxide contains 20th century dioxide widely commercial dry batteries standard carbon types occurrence production comprises earth crust 12th abundant crust elements soil contains average atmosphere contains occurs principally lesser extent important ore economically important usually close spatial relation iron land based resources large irregularly distributed known world resources south_africa important deposits ukraine australia india china brazil according estimate ocean floor billion tons attempts find economically viable methods harvesting abandoned 1970s south_africa identified deposits located near northern cape province estimate billion tons south_africa produced million tons topping nations mined south_africa australia china brazil ukraine india fiji import sources ore south_africa australia mexico south_africa france mexico australia contained imports south_africa australia mexico production ore mixed iron ore carbon reduced blast electric arc resulting content pure production iron free produced ore acid subsequent process progressive extraction process involves directly reducing ore natural gas natural gas provides heat needs reducing agent carbon reduces ore form ore travels grinding circuit reduce particle size ore increasing surface area aid ore added tank acid iron ratio iron dioxide form iron process yields approximately recovery sent facility cia project howard hughes commissioned ship hughes explorer cover story harvesting sea floor triggered rush activity collect actually practical real mission hughes explorer raise sunken soviet submarine goal soviet code books applications satisfactory substitute major applications minor applications viable steel essential iron steel production virtue fixing properties including component accounted demand presently range total demand uses key component low cost steel small amounts improve steel high temperatures forming high melting preventing formation liquid iron grain boundaries content reaches steel dominant feature decreases higher concentrations reaches acceptable level steel containing high strength steel discovered robert known steel british military steel helmets later military aluminium second largest application aluminum aluminium roughly increased resistance grains absorb lead resistant aluminium cans year million tonnes consumed tonnes uses gasoline boost rating reduce engine knocking unusual compound state dioxide reagent organic chemistry group adjacent ring dioxide antiquity greenish glass trace amounts iron contamination manufacture oxygen drying black preparations brown pigment paint constituent natural original type dry cell battery electron material carbon type cells dioxide reduced preventing formation hydrogen battery material functions newer batteries usually battery cells use basic reaction different mixture tons dioxide purpose metal occasionally coins united_states coin use wartime copper traditionally production coins shortage metal war substituted available silver resulting copper silver dollar coins example dollar presidential coins brass containing pure copper core cases dollar use coin duplicate electromagnetic properties previous sized valued coin mechanisms machines case later dollar coins intended duplicate properties copper previous susan anthony dollar compounds coloring glass brown color result compounds glass industry compounds effects iii iron induce strong green color glass forming colored iron iii slightly pink color iron iii larger quantities produce pink colored glass biological role important element human health essential development system excessive exposure intake lead condition known disorder causes death symptoms similar disease classes large includes reverse hiv contain best known containing containing type present bacteria fact keeping origin theory probably ancient nearly organisms living presence oxygen use deal toxic effects formed electron reduction exceptions bacteria include related use different mechanism suggesting path evolution function life reference intake year old human male day food estimated upper limit daily intake avoid estimates females children generally essential minimum intake unknown rare human body contains bones soft tissue remainder concentrated liver human brain bound notably important oxygen evolution plants oxygen evolving complex contained membranes responsible terminal water light reactions core containing fulfill requirement broad spectrum plant contain precautions compounds toxic widespread metals copper exposure exceed ceiling value short periods level poisoning linked impaired motor skills disorders exhibits higher compounds fatal dose fatal occurred strong effect leads membrane example affected limited absorbed small shows severe effects liver study suggested possible link central nervous system rats exposure united_states regulated safety health administration people exposed workplace breathing set legal limit exposure limit exposure workplace hour national institute safety health set recommended exposure limit hour short term limit levels immediately dangerous life health generally exposure ambient air concentrations excess lead induced symptoms increased protein expression human kidney cells associated decreased concentration characterized reversal reduced diminished environmental health concerns drinking water greater according results study higher levels exposure drinking water associated increased intellectual reduced intelligence school age children long term exposure naturally occurring shower water puts million americans risk data indicates human body recover certain adverse effects exposure stopped body clear excess gasoline gasoline replace lead compounds improve rating low petroleum reduces engine knock agent action groups containing tend form damage exhaust need lead merely historic modern reformation processes create increased ratings directly mixture non reformed universal developed countries japan etc usa provide lowest price volume motor lowest taxation rate combined legislation fuel content year encouraged use compared levels air dropped racing competitions specifically ban compounds racing fuel contains elevated atmospheric concentrations strongly automobile traffic density role disorders frequently associated rare disorder associated excessive historically persons employed production processing risk developing current health safety regulations protect workers developed nations disorder described british academic john studied patients disorder early stages person experience depression mood swings behaviors early symptoms way late stage resembles disease symptoms include weakness slowed speech face forward leaning inability walk backwards falling general problems balance unlike disease associated loss smell patients typically treatment symptoms late stage severe time source exposure removed brain levels return normal childhood developmental disorders recent studies attempt examine effects chronic low dose child development earliest study conducted chinese province drinking water contaminated improper sewage irrigation contained concentrations considered safe time study world health organization children sampled years age province displayed lower performance tests manual short term memory visual identification compared children area recently study year old children bangladesh showed relationship concentration water diminished scores study conducted quebec examined school children ages living homes received water containing controls lived homes received water children experimental group showed increased behavior current maximum safe concentration rules diseases protein called major absorption major blood brain barrier transports nasal proposed mechanism leads stress mitochondrial proteins