Editing Lithium (section)

== Properties ==
=== Atomic and physical ===
[[File:Limetal.JPG|thumb|upright=0.7|left|Lithium ingots with a thin layer of black nitride tarnish]]
The [[alkali metal]]s are also called the lithium family, after its leading element. Like the other alkali metals (which are [[sodium]] (Na), [[potassium]] (K), [[rubidium]] (Rb), [[caesium]] (Cs), and [[francium]] (Fr)), lithium has a single [[valence electron]] that, in the presence of solvents, is easily released to form Li<sup>+</sup>.<ref name="krebs" /> Because of this, lithium is a good conductor of heat and electricity as well as a highly reactive element, though it is the least reactive of the alkali metals. Lithium's lower reactivity is due to the proximity of its valence electron to its [[atomic nucleus|nucleus]] (the remaining [[Two-electron atom|two electrons]] are in the [[s-orbital|1s orbital]], much lower in energy, and do not participate in chemical bonds).<ref name="krebs" /> Molten lithium is significantly more reactive than its solid form.<ref>{{Cite journal |last1=Huang |first1=Chuanfu |last2=Kresin |first2=Vitaly V. |date=June 2016 |title=Note: Contamination-free loading of lithium metal into a nozzle source |journal=Review of Scientific Instruments |language=en |volume=87 |issue=6 |page=066105 |doi=10.1063/1.4953918 |pmid=27370506 |issn=0034-6748 |bibcode=2016RScI...87f6105H}}</ref><ref>{{Cite book |title=The chemistry of the liquid alkali metals |author=Addison, C. C. |date=1984 |publisher=Wiley |isbn=978-0-471-90508-0 |location=Chichester [West Sussex] |oclc=10751785}}</ref>

Lithium metal is soft enough to be cut with a knife. It is silvery-white. In air it oxidizes to [[lithium oxide]].<ref name="krebs" /> Its [[melting point]] of {{Cvt|180.50|C|K F|disp=|abbr=unit}}<ref name="pubchemLithium">{{cite web |title=PubChem Element Summary for AtomicNumber 3, Lithium |url=https://pubchem.ncbi.nlm.nih.gov/element/Lithium |work=National Center for Biotechnology Information |date=2021 |access-date=10 September 2021 |archive-date=10 September 2021 |archive-url=https://web.archive.org/web/20210910175321/https://pubchem.ncbi.nlm.nih.gov/element/Lithium |url-status=live}}</ref> and its [[boiling point]] of {{Cvt|1342|C|K F|disp=|abbr=unit}}<ref name="pubchemLithium" /> are each the highest of all the alkali metals while its [[density]] of 0.534 [[Density#Unit|g/cm<sup>3</sup>]] is the lowest.

Lithium has a very low density (0.534&nbsp;g/cm<sup>3</sup>), comparable with [[pine wood]].<ref>{{Cite web |url=https://education.jlab.org/itselemental/ele003.html |title=It's Elemental – The Element Lithium |website=education.jlab.org |access-date=9 October 2019 |archive-date=5 October 2019 |archive-url=https://web.archive.org/web/20191005165125/https://education.jlab.org/itselemental/ele003.html |url-status=live}}</ref> It is the least dense of all elements that are solids at room temperature; the next lightest solid element (potassium, at 0.862&nbsp;g/cm<sup>3</sup>) is more than 60% denser. Apart from [[helium]] and [[hydrogen]], as a solid it is less dense than any other element as a liquid, being only two-thirds as dense as [[liquid nitrogen]] (0.808&nbsp;g/cm<sup>3</sup>).<ref>{{cite web |url=http://encyclopedia.airliquide.com/Encyclopedia.asp?LanguageID=11&CountryID=19&Formula=&GasID=5&UNNumber=&EquivGasID=32&VolLiquideBox=&MasseLiquideBox=&VolGasBox=&MasseGasBox=&RD20=29&RD9=8&RD6=64&RD4=2&RD3=22&RD8=27&RD2=20&RD18=41&RD7=18&RD13=71&RD16=35&RD12=31&RD19=34&RD24=62&RD25=77&RD26=78&RD28=81&RD29=82 |title=Nitrogen, N2, Physical properties, safety, MSDS, enthalpy, material compatibility, gas liquid equilibrium, density, viscosity, inflammability, transport properties |publisher=Encyclopedia.airliquide.com |access-date=29 September 2010 |url-status=live |archive-url=https://web.archive.org/web/20110721162642/http://encyclopedia.airliquide.com/Encyclopedia.asp?LanguageID=11&CountryID=19&Formula=&GasID=5&UNNumber=&EquivGasID=32&VolLiquideBox=&MasseLiquideBox=&VolGasBox=&MasseGasBox=&RD20=29&RD9=8&RD6=64&RD4=2&RD3=22&RD8=27&RD2=20&RD18=41&RD7=18&RD13=71&RD16=35&RD12=31&RD19=34&RD24=62&RD25=77&RD26=78&RD28=81&RD29=82 |archive-date=21 July 2011}}</ref> Lithium can float on the lightest hydrocarbon oils and is one of only three metals that can float on water, the other two being [[sodium]] and [[potassium]].
[[File:Lithium element.jpg|thumb|left|upright=0.7|Lithium floating in oil]]
Lithium's [[coefficient of thermal expansion]] is twice that of [[aluminium]] and almost four times that of [[iron]].<ref>{{cite web |url=http://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html |title=Coefficients of Linear Expansion |publisher=Engineering Toolbox |archive-url=https://web.archive.org/web/20121130215248/http://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html |archive-date=30 November 2012 |access-date=9 January 2011}}</ref> Lithium is [[superconductive]] below 400 [[microkelvin|μK]] at standard pressure<ref>{{cite journal |last1=Tuoriniemi |first1=Juha |last2=Juntunen-Nurmilaukas |first2=Kirsi |last3=Uusvuori |first3=Johanna |last4=Pentti |first4=Elias |last5=Salmela |first5=Anssi |last6=Sebedash |first6=Alexander |title=Superconductivity in lithium below 0.4 millikelvin at ambient pressure |journal=Nature |volume=447 |issue=7141 |pages=187–9 |year=2007 |pmid=17495921 |doi=10.1038/nature05820 |bibcode=2007Natur.447..187T |s2cid=4430500 |url=https://zenodo.org/record/996565 |access-date=20 April 2018 |archive-url=https://web.archive.org/web/20190625233052/https://zenodo.org/record/996565 |archive-date=25 June 2019 |url-status=live}}</ref> and at higher temperatures (more than 9 K) at very high pressures (>20 GPa).<ref>{{Cite journal |doi=10.1126/science.1078535 |date=2002 |author=Struzhkin, V. V. |author2=Eremets, M. I. |author3=Gan, W |author4=Mao, H. K. |author5=Hemley, R. J. |title=Superconductivity in dense lithium |volume=298 |issue=5596 |pages=1213–5 |pmid=12386338 |journal=Science |bibcode=2002Sci...298.1213S |s2cid=21030510}}</ref> At temperatures below 70 K, lithium, like sodium, undergoes [[diffusionless transformations|diffusionless phase change transformations]]. At 4.2 K it has a [[rhombohedral crystal system]] (with a nine-layer repeat spacing); at higher temperatures it transforms to [[face-centered cubic]] and then [[body-centered cubic]]. At liquid-helium temperatures (4 K) the rhombohedral structure is prevalent.<ref name="overhauser">{{Cite journal |first=A. W. |last=Overhauser |title=Crystal Structure of Lithium at 4.2 K |doi=10.1103/PhysRevLett.53.64 |volume=53 |issue=1 |pages=64–65 |date=1984 |journal=Physical Review Letters |bibcode=1984PhRvL..53...64O}}</ref> Multiple allotropic forms have been identified for lithium at high pressures.<ref>{{cite journal |last1=Schwarz |first1=Ulrich |title=Metallic high-pressure modifications of main group elements |journal=Zeitschrift für Kristallographie |volume=219 |pages=376–390 |date=2004 |doi=10.1524/zkri.219.6.376.34637 |issue=6–2004 |bibcode=2004ZK....219..376S |s2cid=56006683}}</ref>

Lithium has a mass [[specific heat capacity]] of 3.58 kilojoules per kilogram-kelvin, the highest of all solids.<ref name="CRC">{{Cite book |author=Hammond, C. R. |title=The Elements, in Handbook of Chemistry and Physics |date=2000 |publisher=CRC press |isbn=978-0-8493-0481-1 |edition=81st}}{{page needed|date=December 2016}}</ref><ref>[https://web.archive.org/web/20140823211840/http://hilltop.bradley.edu/~spost/THERMO/solidcp.pdf SPECIFIC HEAT OF SOLIDS]. bradley.edu</ref> Because of this, lithium metal is often used in [[coolant]]s for [[heat transfer]] applications.<ref name="CRC" />

=== Isotopes ===
{{Main|Isotopes of lithium}}
Naturally occurring lithium is composed of two stable [[isotope]]s, <sup>6</sup>Li and <sup>7</sup>Li, the latter being the more abundant (95.15% [[natural abundance]]).{{CIAAW2013}}<ref>{{NUBASE2020}}</ref> Both natural isotopes have anomalously low [[nuclear binding energy]] per nucleon (compared to the neighboring elements on the [[Periodic chart of the elements|periodic table]], [[helium]] and [[beryllium]]); lithium is the only low numbered element that can produce net energy through [[nuclear fission]]. The two lithium nuclei have lower binding energies per nucleon than any other stable nuclides other than [[hydrogen-1]], [[deuterium]] and [[helium-3]].<ref name="bind">[[:File:Binding energy curve - common isotopes.svg]] shows binding energies of stable nuclides graphically; the source of the data-set is given in the figure background.</ref> As a result of this, though very light in atomic weight, lithium is less common in the Solar System than 25 of the first 32 chemical elements.<ref name="Lodders2003" /> Seven [[radioisotope]]s have been characterized, the most stable being <sup>8</sup>Li with a [[half-life]] of 838 [[millisecond|ms]] and <sup>9</sup>Li with a half-life of 178&nbsp;ms. All of the remaining [[radioactive]] isotopes have half-lives that are shorter than 8.6&nbsp;ms. The shortest-lived isotope of lithium is <sup>4</sup>Li, which decays through [[proton emission]] and has a half-life of 7.6 × 10<sup>−23</sup> s.<ref name="nuclidetable">{{cite web |url=http://www.nndc.bnl.gov/chart/reCenter.jsp?z=104&n=158 |title=Interactive Chart of Nuclides |publisher=Brookhaven National Laboratory |author=Sonzogni, Alejandro |location=National Nuclear Data Center |access-date=6 June 2008 |url-status=live |archive-url=https://web.archive.org/web/20070723192118/http://www.nndc.bnl.gov/chart/reCenter.jsp?z=104&n=158 |archive-date=23 July 2007}}</ref> The <sup>6</sup>Li isotope is one of only [[Stable nuclide#Odd and even proton and neutron count|five stable nuclides]] to have both an odd number of protons and an odd number of neutrons, the other four stable [[Even and odd atomic nuclei#Odd proton, odd neutron|odd-odd nuclides]] being [[deuterium|hydrogen-2]], [[boron-10]], [[nitrogen-14]], and [[tantalum-180m]].<ref>{{cite book |last=Various |editor=Lide, David R. |year=2002 |title=Handbook of Chemistry & Physics |edition=88th |publisher=CRC |url=http://www.hbcpnetbase.com/ |access-date=2008-05-23 |isbn=978-0-8493-0486-6 |oclc=179976746 |archive-date=24 July 2017 |archive-url=https://web.archive.org/web/20170724011402/http://www.hbcpnetbase.com/}}</ref>

<sup>7</sup>Li is one of the [[primordial elements]] (or, more properly, primordial [[nuclide]]s) produced in [[Big Bang nucleosynthesis]].  A small amount of both <sup>6</sup>Li and <sup>7</sup>Li are produced in stars during [[stellar nucleosynthesis]], but it is further "[[Lithium burning|burned]]" as fast as produced.<ref>{{Cite journal |title=Lithium Isotopic Abundances in Metal-poor Halo Stars |date=2006 |journal=The Astrophysical Journal |doi=10.1086/503538 |volume=644 |issue=1 |pages=229–259 |author=Asplund, M. |bibcode=2006ApJ...644..229A |arxiv=astro-ph/0510636 |display-authors=1 |last2=Lambert |first2=David L. |last3=Nissen |first3=Poul Erik |last4=Primas |first4=Francesca |last5=Smith |first5=Verne V. |s2cid=394822}}</ref>    <sup>7</sup>Li can also be generated in [[carbon star]]s.<ref>{{Cite journal |title=Episodic lithium production by extra-mixing in red giants |bibcode=2000A&A...358L..49D |first1=P. A. |last1=Denissenkov |first2=A. |last2=Weiss |journal=Astronomy and Astrophysics |volume=358 |pages=L49–L52 |date=2000 |arxiv=astro-ph/0005356 }}</ref>  Additional small amounts of both <sup>6</sup>Li and <sup>7</sup>Li may be generated from solar wind, cosmic rays hitting heavier atoms, and from early solar system <sup>7</sup>[[Beryllium|Be]] radioactive decay.<ref>{{Cite journal |url=http://sims.ess.ucla.edu/PDF/Chaussidon_et_al_Geochim%20Cosmochim_2006a.pdf |doi=10.1016/j.gca.2005.08.016 |first1=M. |last1=Chaussidon |first2=F. |last2=Robert |first3=K. D. |last3=McKeegan |journal=Geochimica et Cosmochimica Acta |volume=70 |issue=1 |date=2006 |pages=224–245 |title=Li and B isotopic variations in an Allende CAI: Evidence for the in situ decay of short-lived <sup>10</sup>Be and for the possible presence of the short−lived nuclide <sup>7</sup>Be in the early solar system |bibcode=2006GeCoA..70..224C |archive-url=https://web.archive.org/web/20100718065257/http://sims.ess.ucla.edu/PDF/Chaussidon_et_al_Geochim%20Cosmochim_2006a.pdf |archive-date=18 July 2010}}</ref>

Lithium isotopes fractionate substantially during a wide variety of natural processes,<ref>{{Cite journal |date=2004 |first1=H. M. |last1=Seitz |first2=G. P. |last2=Brey |first3=Y. |last3=Lahaye |first4=S. |last4=Durali |first5=S. |last5=Weyer |title=Lithium isotopic signatures of peridotite xenoliths and isotopic fractionation at high temperature between olivine and pyroxenes |journal=Chemical Geology |volume=212 |issue=1–2 |doi=10.1016/j.chemgeo.2004.08.009 |pages=163–177 |bibcode=2004ChGeo.212..163S}}</ref> including mineral formation (chemical precipitation), [[metabolism]], and [[ion exchange]]. Lithium ions substitute for [[magnesium]] and iron in octahedral sites in [[clay]] minerals, where <sup>6</sup>Li is preferred to <sup>7</sup>Li, resulting in enrichment of the light isotope in processes of hyperfiltration and rock alteration. The exotic <sup>11</sup>Li is known to exhibit a [[Halo nucleus|neutron halo]], with 2 neutrons orbiting around its nucleus of 3 protons and 6 neutrons. The process known as [[atomic vapor laser isotope separation|laser isotope separation]] can be used to separate lithium isotopes, in particular <sup>7</sup>Li from <sup>6</sup>Li.<ref>{{Cite book |page=330 |title=Tunable Laser Applications |author=Duarte, F. J |author-link=F. J. Duarte |publisher=CRC Press |date=2009 |isbn=978-1-4200-6009-6}}</ref>

Nuclear weapons manufacture and other nuclear physics applications are a major source of artificial lithium fractionation, with the light isotope <sup>6</sup>Li being retained by industry and military stockpiles to such an extent that it has caused slight but measurable change in the <sup>6</sup>Li to <sup>7</sup>Li ratios in natural sources, such as rivers. This has led to unusual uncertainty in the standardized [[atomic weight]] of lithium, since this quantity depends on the natural abundance ratios of these naturally-occurring stable lithium isotopes, as they are available in commercial lithium mineral sources.<ref name="Coplen2002">{{cite journal |doi=10.1351/pac200274101987 |title=Isotope-abundance variations of selected elements (IUPAC Technical Report) |date=2002 |last1=Coplen |first1=T. B. |last2=Bohlke |first2=J. K. |last3=De Bievre |first3=P. |last4=Ding |first4=T. |last5=Holden |first5=N. E. |last6=Hopple |first6=J. A. |last7=Krouse |first7=H. R. |last8=Lamberty |first8=A. |last9=Peiser |first9=H. S.|last10=N.N. |journal=Pure and Applied Chemistry |volume=74 |issue=10 |page=1987 |display-authors=9 |doi-access=free}}</ref>

Both stable isotopes of lithium can be [[laser cooling|laser cooled]] and were used to produce the first quantum degenerate [[Bose–Einstein condensate|Bose]]–[[Fermionic condensate|Fermi]] mixture.<ref>{{Cite journal |last1=Truscott |first1=Andrew G. |last2=Strecker |first2=Kevin E. |last3=McAlexander |first3=William I. |last4=Partridge |first4=Guthrie B. |last5=Hulet |first5=Randall G. |date=2001-03-30 |title=Observation of Fermi Pressure in a Gas of Trapped Atoms |journal=Science |language=en |volume=291 |issue=5513 |pages=2570–2572 |doi=10.1126/science.1059318 |issn=0036-8075 |pmid=11283362 |bibcode=2001Sci...291.2570T |s2cid=31126288}}</ref>