Editing Nickel (section)

==Properties==

===Atomic and physical properties===
[[File:Ni@CNT2.jpg|thumb|left|[[Transmission electron microscopy|Electron micrograph]] of a Ni nanocrystal inside a single wall [[carbon nanotube]]; scale bar 5&nbsp;nm<ref>{{cite journal|doi=10.1038/srep15033|pmid=26459370|pmc=4602218|title=Nickel clusters embedded in carbon nanotubes as high performance magnets|journal=Scientific Reports|volume=5|page=15033|date=2015|display-authors=4|last1=Shiozawa|first1=Hidetsugu|last2=Briones-Leon|first2=Antonio|last3=Domanov|first3=Oleg|last4=Zechner|first4=Georg|last5=Sato|first5=Yuta|last6=Suenaga|first6=Kazu|last7=Saito|first7=Takeshi|last8=Eisterer|first8=Michael|last9=Weschke|first9=Eugen|last10=Lang|first10=Wolfgang|last11=Peterlik|first11=Herwig|last12=Pichler|first12=Thomas|bibcode=2015NatSR...515033S}}</ref>]]
Nickel is a silvery-white metal with a slight golden tinge that takes a high polish. It is one of only four elements that are [[Ferromagnetism|ferromagnetic]] at or near room temperature; the others are iron, [[cobalt]] and [[gadolinium]]. Its [[Curie temperature]] is {{convert|355|°C|°F|}}, meaning that bulk nickel is non-magnetic above this temperature.<ref>{{cite book |author=Kittel, Charles|title=[[Introduction to Solid State Physics]] |publisher=Wiley |date=1996 |page=449 |isbn=978-0-471-14286-7}}</ref><ref name="CoeySkumryev1999" /> The unit cell of nickel is a [[Cubic crystal system|face-centered cube]]; it has lattice parameter of 0.352&nbsp;nm, giving an [[atomic radius]] of 0.124&nbsp;nm. This crystal structure is stable to pressures of at least 70&nbsp;GPa. Nickel is hard, malleable and [[Ductility|ductile]], and has a relatively high [[Electrical resistivity and conductivity|electrical]] and [[thermal conductivity]] for transition metals.<ref name="crc" /> The high [[compressive strength]] of 34 GPa, predicted for ideal crystals, is never obtained in the real bulk material due to formation and movement of [[dislocation]]s. However, it has been reached in Ni [[nanoparticle]]s.<ref>{{cite journal|doi=10.1038/s41467-018-06575-6|pmid=30291239|pmc=6173750|title=Nickel nanoparticles set a new record of strength|journal=Nature Communications|volume=9|issue=1|pages=4102|year=2018|last1=Sharma|first1=A.|last2=Hickman|first2=J.|last3=Gazit|first3=N.|last4=Rabkin|first4=E.|last5=Mishin|first5=Y.|bibcode=2018NatCo...9.4102S}}</ref>

====Electron configuration dispute====
Nickel has two atomic [[electron configuration]]s, [Ar] 3d{{sup|8}} 4s{{sup|2}} and [Ar] 3d{{sup|9}} 4s{{sup|1}}, which are very close in energy; [Ar] denotes the complete [[argon]] core structure. There is some disagreement on which configuration has the lower energy.<ref name="Scerri" /> Chemistry textbooks quote nickel's electron configuration as [Ar] 4s{{sup|2}} 3d{{sup|8}},<ref>Miessler, G.L. and Tarr, D.A. (1999) ''Inorganic Chemistry'' 2nd ed., Prentice–Hall. p. 38. {{ISBN|0138418918}}.</ref> also written [Ar] 3d{{sup|8}} 4s{{sup|2}}.<ref>Petrucci, R.H. et al. (2002) ''General Chemistry'' 8th ed., Prentice–Hall. p. 950. {{ISBN|0130143294}}.</ref> This configuration agrees with the [[Madelung rule|Madelung energy ordering rule]], which predicts that 4s is filled before 3d. It is supported by the experimental fact that the lowest energy state of the nickel atom is a 3d{{sup|8}} 4s{{sup|2}} energy level, specifically the 3d{{sup|8}}({{sup|3}}F) 4s{{sup|2}} {{sup|3}}F, ''J''&nbsp;=&nbsp;4 level.<ref name="JPCRD">{{cite web |last1=Corliss |first1=Charles |last2=Sugar |first2=Jack |title=Energy levels of nickel, Ni I through Ni XXVIII |page=200 |url=https://srd.nist.gov/jpcrdreprint/1.555638.pdf |publisher=Journal of Physical and Chemical Reference Data |access-date=5 March 2023 |date=15 October 2009 |quote=In this table Ni I = neutral Ni atom, Ni II = Ni+ etc.}}</ref><ref name="NIST">[http://physics.nist.gov/PhysRefData/ASD/levels_form.html NIST Atomic Spectrum Database] {{Webarchive|url=https://web.archive.org/web/20110320190125/http://physics.nist.gov/PhysRefData/ASD/levels_form.html |date=March 20, 2011 }} To read the nickel atom levels, type "Ni 0" or "Ni I" in the Spectrum box and click on Retrieve data.</ref>

However, each of these two configurations splits into several energy levels due to [[fine structure]],<ref name="JPCRD"/><ref name="NIST" /> and the two sets of energy levels overlap. The average energy of states with [Ar] 3d{{sup|9}} 4s{{sup|1}} is actually lower than the average energy of states with [Ar] 3d{{sup|8}} 4s{{sup|2}}. Therefore, the research literature on atomic calculations quotes the ground state configuration as [Ar] 3d{{sup|9}} 4s{{sup|1}}.<ref name="Scerri">{{cite book |url=https://archive.org/details/periodictableits0000scer |url-access=registration |pages=[https://archive.org/details/periodictableits0000scer/page/239 239]–240 |title=The periodic table: its story and its significance |author=Scerri, Eric R. |author-link = Eric Scerri |publisher=Oxford University Press|date=2007 |isbn=978-0-19-530573-9}}</ref>

===Isotopes===
{{Main|Isotopes of nickel}}
The isotopes of nickel range in [[atomic weight]] from 48&nbsp;[[atomic mass unit|u]] ({{chem|48|Ni}}) to 82&nbsp;u ({{chem|82|Ni}}).{{NUBASE2020|ref}}

Natural nickel is composed of five stable [[isotope]]s, {{chem|58|Ni}}, {{chem|60|Ni}}, {{chem|61|Ni}}, {{chem|62|Ni}} and {{chem|64|Ni}}, of which {{chem|58|Ni}} is the most abundant (68.077% [[natural abundance]]).{{NUBASE2020|ref}}

[[Nickel-62]] has the highest [[nuclear binding energy|binding energy]] per nucleon of any [[nuclide]]: 8.7946&nbsp;MeV/nucleon.<ref>{{cite journal|url = http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin2.html#c1|title = The Most Tightly Bound Nuclei|journal = American Journal of Physics|volume = 57|issue = 6|pages = 552|access-date = November 19, 2008|archive-url = https://web.archive.org/web/20110514050922/http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin2.html#c1|archive-date = May 14, 2011|url-status = live|bibcode = 1989AmJPh..57..552S|last1 = Shurtleff|first1 = Richard|last2 = Derringh|first2 = Edward|year = 1989|doi = 10.1119/1.15970}}</ref><ref>{{Cite web|title=Nuclear synthesis|url=http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/nucsyn.html|access-date=2020-10-15|website=hyperphysics.phy-astr.gsu.edu}}</ref> Its binding energy is greater than both [[iron-56|{{chem|56|Fe}}]] and [[iron-58|{{chem|58|Fe}}]], more abundant nuclides often incorrectly cited as having the highest binding energy.<ref name="aip1995">{{cite journal | doi = 10.1119/1.17828 | title=The atomic nuclide with the highest mean binding energy | journal=American Journal of Physics | date=1995 | volume=63 | issue=7 | page=653 | first=M. P. | last=Fewell| bibcode=1995AmJPh..63..653F }}</ref> Though this would seem to predict nickel as the most abundant heavy element in the universe, the high rate of [[photodisintegration]] of nickel in stellar interiors causes iron to be by far the most abundant.<ref name="aip1995" />

Nickel-60 is the daughter product of the [[extinct radionuclide]] [[iron-60|{{chem|60|Fe}}]] (half-life 2.6&nbsp;million years). Due to the long half-life of {{chem|60|Fe}}, its persistence in materials in the [[Solar System]] may generate observable variations in the isotopic composition of {{chem|60|Ni}}. Therefore, the abundance of {{chem|60|Ni}} in extraterrestrial material may give insight into the origin of the Solar System and its early history.<ref>{{cite web |last1=Caldwell |first1=Eric |title=Resources on Isotopes |url=https://wwwrcamnl.wr.usgs.gov/isoig/period/ni_iig.html |publisher=United States Geological Survey |access-date=20 May 2022}}</ref>

At least 26 nickel [[radioisotope]]s have been characterized; the most stable are {{chem|59|Ni}} with [[half-life]] 76,000 years, {{chem|63|Ni}} (100 years), and {{chem|56||Ni}} (6 days). All other radioisotopes have half-lives less than 60 hours and most these have half-lives less than 30 seconds. This element also has one [[meta state]].{{NUBASE2020|ref}}

Radioactive nickel-56 is produced by the [[silicon burning process]] and later set free in large amounts in [[Type Ia supernova|type Ia]] [[supernova]]e. The shape of the [[light curve]] of these supernovae at intermediate to late-times corresponds to the decay via [[electron capture]] of {{chem|56|Ni}} to [[cobalt]]-56 and ultimately to iron-56.<ref name="Nucleos">{{cite book |title = Nucleosynthesis and chemical evolution of galaxies|chapter-url = https://archive.org/details/nucleosynthesisc0000page|chapter-url-access = registration| isbn= 978-0-521-55958-4| pages = [https://archive.org/details/nucleosynthesisc0000page/page/154 154–160]| chapter = Further burning stages: evolution of massive stars| first = Bernard Ephraim Julius|last = Pagel| date= 1997| publisher=Cambridge University Press }}</ref> Nickel-59 is a long-lived [[cosmogenic nuclide|cosmogenic]] [[radionuclide]]; half-life 76,000 years. {{chem|59|Ni}} has found many applications in [[isotope geology]]. {{chem|59|Ni}} has been used to date the terrestrial age of [[meteorite]]s and to determine abundances of extraterrestrial dust in ice and [[sediment]]. Nickel-78, with a half-life of 110 milliseconds, is believed an important isotope in [[supernova nucleosynthesis]] of elements heavier than iron.<ref>{{cite web|url = http://www.skyandtelescope.com/news/3310246.html?page=1&c=y|title = Atom Smashers Shed Light on Supernovae, Big Bang|date = April 22, 2005|first = Davide|last = Castelvecchi|access-date = November 19, 2008|archive-url = https://archive.today/20120723105754/http://www.skyandtelescope.com/news/3310246.html?page=1&c=y|archive-date = July 23, 2012|url-status = dead}}</ref> {{sup|48}}Ni, discovered in 1999, is the most proton-rich heavy element isotope known. With 28 [[proton]]s and 20 [[neutron]]s, {{sup|48}}Ni is "[[doubly magic]]", as is {{sup|78}}Ni with 28 protons and 50 neutrons. Both are therefore unusually stable for nuclei with so large a [[neutron–proton ratio|proton–neutron imbalance]].{{NUBASE2020|ref}}<ref>{{cite magazine|last = W|first = P.|title = Twice-magic metal makes its debut – isotope of nickel|magazine=[[Science News]]|date = October 23, 1999|url = http://www.findarticles.com/p/articles/mi_m1200/is_17_156/ai_57799535|archive-url = https://archive.today/20120524134125/http://www.findarticles.com/p/articles/mi_m1200/is_17_156/ai_57799535|url-status = dead|archive-date = May 24, 2012|access-date = September 29, 2006}}</ref>

Nickel-63 is a contaminant found in the support structure of nuclear reactors. It is produced through neutron capture by nickel-62. Small amounts have also been found near nuclear weapon test sites in the South Pacific.<ref>{{cite journal | last1=Carboneau | first1=M. L.| last2=Adams | first2=J. P.| title=Nickel-63| journal=National Low-Level Waste Management Program Radionuclide Report Series| volume=10 | date=1995 | doi=10.2172/31669 | url=https://digital.library.unt.edu/ark:/67531/metadc674188/}}</ref>

===Occurrence===
{{See also|Ore genesis|Category:Nickel minerals}}
[[File:Widmanstatten hand.jpg|thumb|left|[[Widmanstätten pattern]] showing the two forms of nickel–iron, kamacite and taenite, in an octahedrite meteorite]]
Nickel ores are classified as oxides or sulfides.  Oxides include [[laterite]], where the principal mineral mixtures are nickeliferous [[limonite]], (Fe,Ni)O(OH), and [[garnierite]] (a mixture of various hydrous nickel and nickel-rich silicates).<ref name="Mudd 2010 pp. 9–26">{{cite journal |last1=Mudd |first1=Gavin M. |title=Global trends and environmental issues in nickel mining: Sulfides versus laterites |journal=Ore Geology Reviews |date=October 2010 |volume=38 |issue=1–2 |pages=9–26 |doi=10.1016/j.oregeorev.2010.05.003 |bibcode=2010OGRv...38....9M }}</ref> Nickel sulfides commonly exist as solid solutions with iron in minerals such as  [[pentlandite]] and [[pyrrhotite]] with the formula Fe<sub>9−x</sub>Ni<sub>x</sub>S<sub>8</sub> and Fe<sub>7−x</sub>Ni<sub>x</sub>S<sub>6</sub>, respectively. Other common Ni-containing minerals are [[millerite]] and the [[arsenide]]  [[niccolite]].<ref>[http://www.npi.gov.au/substances/nickel/index.html National Pollutant Inventory – Nickel and compounds Fact Sheet] {{Webarchive|url=https://web.archive.org/web/20111208083730/http://www.npi.gov.au/substances/nickel/index.html |date=December 8, 2011 }}. Npi.gov.au. Retrieved on January 9, 2012.</ref><ref>{{Cite web|title=Nickel reserves worldwide by country 2020|url=https://www.statista.com/statistics/273634/nickel-reserves-worldwide-by-country/|access-date=2021-03-29|website=Statista}}</ref>

Identified land-based resources throughout the world averaging 1% nickel or greater comprise at least 130&nbsp;million tons of nickel (about the double of known reserves). About 60% is in [[laterites]] and 40% in sulfide deposits.<ref name="USGSCS2019">{{cite web|first = Peter H.|last = Kuck|publisher = United States Geological Survey|title = Mineral Commodity Summaries 2019: Nickel|url = https://minerals.usgs.gov/minerals/pubs/commodity/nickel/mcs-2019-nicke.pdf|access-date = March 18, 2019|archive-url = https://web.archive.org/web/20190421125020/https://minerals.usgs.gov/minerals/pubs/commodity/nickel/mcs-2019-nicke.pdf|archive-date = April 21, 2019|url-status = live}}</ref>

On [[geophysics|geophysical]] evidence, most of the nickel on Earth is believed to be in Earth's [[outer core|outer]] and [[inner core]]s. [[Kamacite]] and [[taenite]] are naturally occurring [[alloy]]s of iron and nickel. For kamacite, the alloy is usually in the proportion of 90:10 to 95:5, though impurities (such as [[cobalt]] or [[carbon]]) may be present. Taenite is 20% to 65% nickel. Kamacite and taenite are also found in [[nickel iron meteorite]]s.<ref>{{cite journal|title = Trace element partitioning between taenite and kamacite – Relationship to the cooling rates of iron meteorites|last1= Rasmussen|first1=K. L.|last2= Malvin|first2=D. J.|last3= Wasson|first3=J. T.|journal=Meteoritics |volume= 23|date = 1988|pages = a107–112 |bibcode= 1988Metic..23..107R|doi = 10.1111/j.1945-5100.1988.tb00905.x|issue = 2}}</ref>

Nickel is commonly found in [[iron meteorite]]s as the alloys [[kamacite]] and [[taenite]]. Nickel in meteorites was first detected in 1799 by [[Joseph Proust|Joseph-Louis Proust]], a French chemist who then worked in Spain. Proust analyzed samples of the meteorite from [[Campo del Cielo]] (Argentina), which had been obtained in 1783 by Miguel Rubín de Celis, discovering the presence in them of nickel (about 10%) along with iron.<ref>{{Cite book|title=Construyendo la Tabla Periódica|last=Calvo|first=Miguel|publisher=Prames|year=2019|isbn=978-84-8321-908-9|location=Zaragoza, Spain|pages=118}}</ref>