Editing Lawrencium (section)

==Characteristics==

===Physical===
Lawrencium is the last [[actinide]]. Authors considering the subject generally consider it a [[group 3 element]], along with [[scandium]], [[yttrium]], and [[lutetium]], as its filled f-shell is expected to make it resemble the other [[period 7 element|7th-period]] [[transition metal]]s. In the [[periodic table]], it is to the right of the actinide [[nobelium]], to the left of the 6d transition metal [[rutherfordium]], and under the lanthanide lutetium with which it shares many physical and chemical properties. Lawrencium is expected to be a solid under normal conditions and have a [[hexagonal close-packed]] crystal structure (<sup>''c''</sup>/<sub>''a''</sub>&nbsp;=&nbsp;1.58), similar to its lighter [[congener (chemistry)|congener]] lutetium, though this is not yet known experimentally.<ref name="hcp" /> The [[enthalpy]] of [[sublimation (phase transition)|sublimation]] of lawrencium is estimated at 352&nbsp;kJ/mol, close to the value of lutetium and strongly suggesting that metallic lawrencium is trivalent with three electrons [[delocalized electron|delocalized]], a prediction also supported by a systematic extrapolation of the values of [[heat of vaporization]], [[bulk modulus]], and [[atomic volume]] of neighboring elements to lawrencium.<ref name="Silva1644">{{harvnb|Silva|2011|p=1644}}</ref> This makes it unlike the immediately preceding late actinides which are known to be (fermium and mendelevium) or expected to be (nobelium) divalent.<ref>{{harvnb|Silva|2011|p=1639}}</ref> The estimated enthalpies of vaporization show that lawrencium deviates from the trend of the late actinides and instead matches the trend of the succeeding 6d elements rutherfordium and dubnium,<ref name=insights/><ref name=Jensen2015/> consistent with lawrencium's interpretation as a group 3 element.<ref name="Jensen2015">{{cite journal |last1=Jensen |first1=William B. |date=2015 |title=The positions of lanthanum (actinium) and lutetium (lawrencium) in the periodic table: an update |url=https://link.springer.com/article/10.1007/s10698-015-9216-1 |journal=Foundations of Chemistry |volume=17 |issue= |pages=23–31 |doi=10.1007/s10698-015-9216-1 |s2cid=98624395 |access-date=28 January 2021 |archive-date=30 January 2021 |archive-url=https://web.archive.org/web/20210130011116/https://link.springer.com/article/10.1007/s10698-015-9216-1 |url-status=live }}</ref> Some scientists prefer to end the actinides with nobelium and consider lawrencium to be the first transition metal of the seventh period.<ref>{{cite web |url=https://www.webelements.com/ |title=WebElements |last=Winter |first=Mark |date=1993–2022 |website= |publisher=The University of Sheffield and WebElements Ltd, UK |access-date=5 December 2022 |quote=}}</ref><ref>{{cite book |last=Cowan |first=Robert D. |author-link= |date=1981 |title=The Theory of Atomic Structure and Spectra |url= |location= |publisher=University of California Press |page=598 |isbn=9780520906150}}</ref>

Lawrencium is expected to be a trivalent, silvery metal, easily [[redox|oxidized]] by air, [[steam]], and [[acid]]s,<ref name="Emsley2011">{{cite book|author=John Emsley|title=Nature's Building Blocks: An A-Z Guide to the Elements|url=https://books.google.com/books?id=4BAg769RfKoC&pg=PA368|date= 2011|publisher=Oxford University Press|isbn=978-0-19-960563-7|pages=278–9}}</ref> and having an atomic volume similar to that of lutetium and a trivalent [[metallic radius]] of 171&nbsp;[[picometer|pm]].<ref name="Silva1644" /> It is expected to be a rather heavy metal with a density of around 14.4&nbsp;g/cm<sup>3</sup>.<ref name="density" /> It is also predicted to have a [[melting point]] of around 1900&nbsp;[[kelvin|K]] (1600&nbsp;[[Celsius|°C]]<!--DON'T CHANGE IT, FALSE PRECISION OTHERWISE-->), not far from the value for lutetium (1925&nbsp;K).<ref>{{cite book | editor = Lide, D. R. | title = CRC Handbook of Chemistry and Physics | edition = 84th | location = Boca Raton, FL | publisher = CRC Press | date = 2003 }}</ref>

===Chemical===
[[File:F-block elution sequence.png|thumb|right|upright=1.4|Elution sequence of the late trivalent lanthanides and actinides, with ammonium α-HIB as eluant: the broken curve for lawrencium is a prediction.]]
In 1949, [[Glenn T. Seaborg]], who devised the [[actinide concept]], predicted that element 103 (lawrencium) should be the last actinide and that the {{chem2|Lr(3+)}} ion should be about as stable as {{chem2|Lu(3+)}} in [[aqueous solution]]. It was not until decades later that element 103 was finally conclusively synthesized and this prediction was experimentally confirmed.<ref name="Silva16447">{{harvnb|Silva|2011|pp=1644–7}}</ref>

Studies on the element, performed in 1969, showed that lawrencium reacts with [[chlorine]] to form a product that was most likely the trichloride, {{chem2|LrCl3}}. Its [[volatility (chemistry)|volatility]] was found to be similar to the chlorides of [[curium]], [[fermium]], and [[nobelium]] and much less than that of [[rutherfordium]] chloride. In 1970, chemical studies were performed on 1500&nbsp;atoms of <sup>256</sup>Lr, comparing it with divalent ([[nobelium|No]], [[barium|Ba]], [[radium|Ra]]), trivalent ([[fermium|Fm]], [[californium|Cf]], [[curium|Cm]], [[americium|Am]], [[actinium|Ac]]), and tetravalent ([[thorium|Th]], [[plutonium|Pu]]) elements. It was found that lawrencium [[extraction (chemistry)|coextracted]] with the trivalent ions, but the short half-life of <sup>256</sup>Lr precluded a confirmation that it [[elution|eluted]] ahead of {{chem2|[[mendelevium|Md]](3+)}} in the elution sequence.<ref name="Silva16447" /> Lawrencium occurs as the trivalent {{chem2|Lr(3+)}} ion in aqueous solution and hence its compounds should be similar to those of the other trivalent actinides: for example, lawrencium(III) [[fluoride]] ({{chem2|LrF3}}) and [[hydroxide]] ({{chem2|Lr(OH)3}}) should both be insoluble in water.<ref name="Silva16447" /> Due to the [[lanthanide contraction|actinide contraction]], the [[ionic radius]] of {{chem2|Lr(3+)}} should be smaller than that of {{chem2|Md(3+)}}, and it should elute ahead of {{chem2|Md(3+)}} when [[ammonium α-hydroxyisobutyrate]] (ammonium α-HIB) is used as an eluant.<ref name="Silva16447" /> Later 1987 experiments on the longer-lived isotope <sup>260</sup>Lr confirmed lawrencium's trivalency and that it eluted in roughly the same place as [[erbium]], and found that lawrencium's ionic radius was {{val|88.6|0.3|u=[[picometer|pm]]}}, larger than would be expected from simple extrapolation from [[periodic trend]]s.<ref name="Silva16447" /> Later 1988 experiments with more lawrencium atoms refined this to {{val|88.1|0.1|u=pm}} and calculated an [[enthalpy of hydration]] value of {{val|−3685|13|u=kJ/mol}}.<ref name="Silva16447" /> It was also found that the actinide contraction at the end of the actinides was larger than the analogous lanthanide contraction, with the exception of the last actinide, lawrencium: the cause was speculated to be relativistic effects.<ref name="Silva16447" />

It has been speculated that the 7s electrons are relativistically stabilized, so that in reducing conditions, only the 7p<sub>1/2</sub> electron would be ionized, leading to the monovalent {{chem2|Lr(+)}} ion. However, all experiments to reduce {{chem2|Lr(3+)}} to {{chem2|Lr(2+)}} or {{chem2|Lr(+)}} in aqueous solution were unsuccessful, similarly to lutetium. On the basis of this, the [[standard electrode potential]] of the ''E''°({{chem2|Lr(3+) → Lr(+)}}) couple was calculated to be less than −1.56&nbsp;[[volt|V]], indicating that the existence of {{chem2|Lr(+)}} ions in aqueous solution was unlikely. The upper limit for the ''E''°({{chem2|Lr(3+) → Lr(2+)}}) couple was predicted to be −0.44&nbsp;V: the values for ''E''°({{chem2|Lr(3+) → Lr}}) and ''E''°({{chem2|Lr(4+) → Lr(3+)}}) are predicted to be −2.06&nbsp;V and +7.9&nbsp;V.<ref name="Silva16447" /> The stability of the group oxidation state in the 6d transition series decreases as [[rutherfordium|Rf]]<sup>IV</sup> &gt; [[dubnium|Db]]<sup>V</sup> &gt; [[seaborgium|Sg]]<sup>VI</sup>, and lawrencium continues the trend with Lr<sup>III</sup> being more stable than Rf<sup>IV</sup>.<ref>{{cite book| title = The Chemistry of the Actinide and Transactinide Elements| editor1-last = Morss|editor2-first = Norman M.| editor2-last = Edelstein| editor3-last = Fuger|editor3-first = Jean| last1 = Hoffman|first1 = Darleane C.|last2=Lee |first2=Diana M. |last3=Pershina |first3=Valeria |chapter = Transactinides and the future elements| publisher = [[Springer Science+Business Media]]| year = 2006| isbn = 1-4020-3555-1| location = Dordrecht, The Netherlands| edition = 3rd| ref = CITEREFHaire2006| page=1686}}</ref>

In the molecule lawrencium dihydride ({{chem2|LrH2}}), which is predicted to be [[bent molecular geometry|bent]], the 6d orbital of lawrencium is not expected to play a role in the bonding, unlike that of [[lanthanum dihydride]] ({{chem2|LaH2}}). {{chem2|LaH2}} has La–H bond distances of 2.158&nbsp;Å, while {{chem2|LrH2}} should have shorter Lr–H bond distances of 2.042&nbsp;Å due to the relativistic contraction and stabilization of the 7s and 7p orbitals involved in the bonding, in contrast to the core-like 5f subshell and the mostly uninvolved 6d subshell. In general, molecular {{chem2|LrH2}} and LrH are expected to resemble the corresponding [[thallium]] species (thallium having a 6s<sup>2</sup>6p<sup>1</sup> valence configuration in the gas phase, like lawrencium's 7s<sup>2</sup>7p<sup>1</sup>) more than the corresponding [[lanthanide]] species.<ref>{{cite journal|last1=Balasubramanian|first1=K.|date=4 December 2001|title=Potential energy surfaces of Lawrencium and Nobelium dihydrides (LrH<sub>2</sub> and NoH<sub>2</sub>)|journal=Journal of Chemical Physics|volume=116|issue=9|pages=3568–75|bibcode=2002JChPh.116.3568B|doi=10.1063/1.1446029}}</ref> The electron configurations of {{chem2|Lr(+)}} and {{chem2|Lr(2+)}} are expected to be 7s<sup>2</sup> and 7s<sup>1</sup> respectively. However, in species where all three valence electrons of lawrencium are ionized to give at least formally the {{chem2|Lr(3+)}} cation, lawrencium is expected to behave like a typical actinide and the heavier congener of lutetium, especially because the first three ionization potentials of lawrencium are predicted to be similar to those of lutetium. Hence, unlike thallium but like lutetium, lawrencium would prefer to form {{chem2|LrH3}} than LrH, and Lr[[metal carbonyl|CO]] is expected to be similar to the also unknown LuCO, both metals having valence configuration σ<sup>2</sup>π<sup>1</sup> in their monocarbonyls. The pπ–dπ bond is expected to be seen in {{chem2|LrCl3}} just as it is for {{chem2|LuCl3}} and more generally all the {{chem2|LnCl3}}. The complex anion {{chem2|[Lr(C5H4SiMe3)3](−)}} is expected to be stable with a configuration of 6d<sup>1</sup> for lawrencium; this 6d orbital would be [[HOMO/LUMO|its highest occupied molecular orbital]]. This is analogous to the electronic structure of the analogous lutetium compound.<ref name=peculiar>
{{cite journal |last1=Xu |first1=Wen-Hua |last2=Pyykkö |first2=Pekka |date=8 June 2016 |url=http://pubs.rsc.org/-/content/articlehtml/2016/cp/c6cp02706g |title=Is the chemistry of lawrencium peculiar |journal=Phys. Chem. Chem. Phys. |volume=2016 |issue=18 |pages=17351–5 |doi=10.1039/c6cp02706g |pmid=27314425 |access-date=24 April 2017|bibcode=2016PCCP...1817351X |hdl=10138/224395 |s2cid=31224634 |hdl-access=free }}</ref>

===Atomic===
Lawrencium has three [[valence electron]]s: the 5f electrons are in the atomic core.<ref name=jensenlaw>{{cite web|url=http://www.che.uc.edu/jensen/W.%20B.%20Jensen/Reprints/081.%20Periodic%20Table.pdf|last1=Jensen|first1=William B.|authorlink=William B. Jensen|title=The Periodic Law and Table|date=2000|archive-url=https://web.archive.org/web/20201110113324/http://www.che.uc.edu/jensen/W.%20B.%20Jensen/Reprints/081.%20Periodic%20Table.pdf |access-date=10 December 2022|archive-date=2020-11-10 }}</ref> In 1970, it was predicted that the ground-state [[electron configuration]] of lawrencium was [Rn]5f<sup>14</sup>6d<sup>1</sup>7s<sup>2</sup> (ground state [[term symbol]] <sup>2</sup>D<sub>3/2</sub>), per the [[Aufbau principle]] and conforming to the [Xe]4f<sup>14</sup>5d<sup>1</sup>6s<sup>2</sup> configuration of lawrencium's lighter homolog lutetium.<ref name="Silva16434">{{harvnb|Silva|2011|pp=1643–4}}</ref> But the next year, calculations were published that questioned this prediction, instead expecting an anomalous [Rn]5f<sup>14</sup>7s<sup>2</sup>7p<sup>1</sup> configuration.<ref name="Silva16434" /> Though early calculations gave conflicting results,<ref>{{cite journal|last1 = Nugent|first1 = L. J.|last2 = Vander Sluis|first2 = K. L.|last3 = Fricke|first3 = Burhard|last4 = Mann|first4 = J. B.|title = Electronic configuration in the ground state of atomic lawrencium|url = https://kobra.bibliothek.uni-kassel.de/bitstream/urn:nbn:de:hebis:34-2008091523764/1/Fricke_electronic_1974.pdf|archive-url = https://web.archive.org/web/20081219162209/https://kobra.bibliothek.uni-kassel.de/bitstream/urn:nbn:de:hebis:34-2008091523764/1/Fricke_electronic_1974.pdf|url-status = dead|archive-date = December 19, 2008|journal = [[Physical Review|Phys. Rev. A]]|volume = 9|issue = 6|pages = 2270–72|date = 1974|doi = 10.1103/PhysRevA.9.2270|bibcode = 1974PhRvA...9.2270N}}</ref> more recent studies and calculations confirm the s<sup>2</sup>p suggestion.<ref>{{cite journal |last1 = Eliav |first1 = E. |last2 = Kaldor |first2= U. |last3 = Ishikawa |first3 = Y. |title = Transition energies of ytterbium, lutetium, and lawrencium by the relativistic coupled-cluster method |journal = [[Physical Review|Phys. Rev. A]]|volume = 52|issue = 1 |pages = 291–296 |date = 1995 |doi = 10.1103/PhysRevA.52.291|pmid = 9912247 |bibcode = 1995PhRvA..52..291E }}</ref><ref>{{cite journal|last = Zou|first = Yu|author2=Froese Fischer C. |title = Resonance Transition Energies and Oscillator Strengths in Lutetium and Lawrencium|journal = [[Physical Review Letters|Phys. Rev. Lett.]] |volume = 88|page = 183001|date = 2002|pmid=12005680|doi=10.1103/PhysRevLett.88.023001|bibcode = 2001PhRvL..88b3001M|issue = 2 |last3 = Uiterwaal|first3 = C.|last4 = Wanner|first4 = J.|last5 = Kompa|first5 = K.-L.| s2cid=18391594 |url = http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1011&context=physicsuiterwaal}}</ref> 1974 [[relativistic quantum chemistry|relativistic]] calculations concluded that the energy difference between the two configurations was small and that it was uncertain which was the ground state.<ref name="Silva16434" /> Later 1995 calculations concluded that the s<sup>2</sup>p configuration should be energetically favored, because the spherical s and p<sub>1/2</sub> [[atomic orbital|orbitals]] are nearest to the [[atomic nucleus]] and thus move quickly enough that their relativistic mass increases significantly.<ref name="Silva16434" />

In 1988, a team of scientists led by Eichler calculated that lawrencium's [[enthalpy of adsorption]] on metal sources would differ enough depending on its electron configuration that it would be feasible to carry out experiments to exploit this fact to measure lawrencium's electron configuration.<ref name="Silva16434" /> The s<sup>2</sup>p configuration was expected to be more [[volatility (chemistry)|volatile]] than the s<sup>2</sup>d configuration, and be more similar to that of the [[p-block]] element [[lead]]. No evidence for lawrencium being volatile was obtained and the lower limit for the enthalpy of adsorption of lawrencium on [[quartz]] or [[platinum]] was significantly higher than the estimated value for the s<sup>2</sup>p configuration.<ref name="Silva16434" />

[[File:First Ionization Energy blocks.svg|thumb|right|512px|First ionization energy ([[electronvolt|eV]]) plotted against [[atomic number]], in units [[Electronvolt|eV]]. Predicted values are used beyond rutherfordium (element 104). Lawrencium (element 103) has a very low first ionization energy, fitting the start of the d-block trend better than the end of the f-block trend before it.<ref name=JensenLr/>]]
In 2015, the first ionization energy of lawrencium was measured, using the isotope <sup>256</sup>Lr.<ref name="Sato"/> The measured value, {{nowrap|4.96{{su|p=+0.08|b=−0.07}} [[electronvolt|eV]]}}, agreed very well with the relativistic theoretical prediction of 4.963(15)&nbsp;eV, and also provided a first step into measuring the first ionization energies of the [[transactinide]]s.<ref name="Sato" /> This value is the lowest among all the lanthanides and actinides, and supports the s<sup>2</sup>p configuration as the 7p<sub>1/2</sub> electron is expected to be only weakly bound. As ionisation energies generally increase left to right in the f-block, this low value suggests that lutetium and lawrencium belong in the d-block (whose trend they follow) and not the f-block. That would make them the heavier congeners of [[scandium]] and [[yttrium]], rather than [[lanthanum]] and [[actinium]].<ref name="JensenLr">{{cite web|url=https://www.che.uc.edu/jensen/W.%20B.%20Jensen/Reprints/251.%20Lawrencium.pdf |title=Some Comments on the Position of Lawrencium in the Periodic Table |last1=Jensen |first1=W. B. |date=2015 |access-date=20 September 2015 |url-status=dead |archive-url=https://web.archive.org/web/20151223091325/https://www.che.uc.edu/jensen/W.%20B.%20Jensen/Reprints/251.%20Lawrencium.pdf |archive-date=23 December 2015 }}</ref> Although some [[alkali metal]]-like behaviour has been predicted,<ref>{{cite web |url=http://www.rsc.org/chemistryworld/2015/04/lawrencium-experiment-could-shake-periodic-table |title=Lawrencium experiment could shake up periodic table |last1=Gunther |first1=Matthew |date=9 April 2015 |website=RSC Chemistry World |access-date=21 September 2015}}</ref> adsorption experiments suggest that lawrencium is trivalent like scandium and yttrium, not monovalent like the alkali metals.<ref name=insights>{{cite journal |last=Haire |first=R. G. |date=11 October 2007 |title=Insights into the bonding and electronic nature of heavy element materials |journal=Journal of Alloys and Compounds |volume=444–5 |pages=63–71 |doi=10.1016/j.jallcom.2007.01.103|url=https://zenodo.org/record/1259091 }}</ref> A lower limit on lawrencium's second ionization energy (&gt;13.3&nbsp;eV) was experimentally found in 2021.<ref>{{cite journal |last1=Kwarsick |first1=Jeffrey T. |last2=Pore |first2=Jennifer L. |first3=Jacklyn M. |last3=Gates |first4=Kenneth E. |last4=Gregorich |first5=John K. |last5=Gibson |first6=Jiwen |last6=Jian |first7=Gregory K. |last7=Pang |first8=David K. |last8=Shuh |date=2021 |title=Assessment of the Second-Ionization Potential of Lawrencium: Investigating the End of the Actinide Series with a One-Atom-at-a-Time Gas-Phase Ion Chemistry Technique |url= https://escholarship.org/uc/item/8mp9k4g0|journal=The Journal of Physical Chemistry A |volume=125 |issue=31 |pages=6818–6828 |doi=10.1021/acs.jpca.1c01961 |pmid=34242037 |bibcode=2021JPCA..125.6818K |osti=1844939 |s2cid=235785891 |access-date=}}</ref>

Even though s<sup>2</sup>p is now known to be the ground-state configuration of the lawrencium atom, ds<sup>2</sup> should be a low-lying excited-state configuration, with an excitation energy variously calculated as 0.156&nbsp;eV, 0.165&nbsp;eV, or 0.626&nbsp;eV.<ref name=peculiar/><!--in the supplementary information--> As such lawrencium may still be considered to be a d-block element, albeit with an anomalous electron configuration (like [[chromium]] or [[copper]]), as its chemical behaviour matches expectations for a heavier analogue of lutetium.<ref name=Jensen2015/>

===Isotopes===
{{main|Isotopes of lawrencium}}

Fourteen isotopes of lawrencium are known, with [[mass number]] 251–262, 264, and 266; all are radioactive.<ref name="Silva1642">{{harvnb|Silva|2011|p=1642}}</ref><ref name="266Lr">{{Cite journal |title=<sup>48</sup>Ca + <sup>249</sup>Bk Fusion Reaction Leading to Element ''Z'' = 117: Long-Lived α-Decaying <sup>270</sup>Db and Discovery of <sup>266</sup>Lr |journal=Physical Review Letters |volume=112 |issue=17 |doi=10.1103/PhysRevLett.112.172501 |date=2014 |last1=Khuyagbaatar |first1=J. |last2=Yakushev |first2=A. |last3=Düllmann |first3=Ch. E. |last4=Ackermann |first4=D. |last5=Andersson |first5=L.-L. |last6=Asai |first6=M. |last7=Block |first7=M. |last8=Boll |first8=R. A. |last9=Brand |first9=H. |last10=Cox |first10=D. M. |last11=Dasgupta |first11=M. |last12=Derkx |first12=X. |last13=Di Nitto |first13=A. |last14=Eberhardt |first14=K. |last15=Even |first15=J. |last16=Evers |first16=M. |last17=Fahlander |first17=C. |last18=Forsberg |first18=U. |last19=Gates |first19=J. M. |last20=Gharibyan |first20=N. |last21=Golubev |first21=P. |last22=Gregorich |first22=K. E. |last23=Hamilton |first23=J. H. |last24=Hartmann |first24=W. |last25=Herzberg |first25=R.-D. |last26=Heßberger |first26=F. P. |last27=Hinde |first27=D. J. |last28=Hoffmann |first28=J. |last29=Hollinger |first29=R. |last30=Hübner |first30=A. |display-authors=1|bibcode = 2014PhRvL.112q2501K |pmid=24836239 |page=172501|url=http://lup.lub.lu.se/search/ws/files/2377958/4432321.pdf |hdl=1885/70327 |s2cid=5949620 |hdl-access=free }}</ref><ref name="255Db" /> Seven [[nuclear isomer]]s are known. The longest-lived isotope, <sup>266</sup>Lr, has a half-life of about ten hours and is one of the longest-lived [[superheavy element|superheavy]] isotopes known to date.<ref>{{cite magazine|author=Clara Moskowitz |author-link= Clara Moskowitz |url=http://www.scientificamerican.com/article/superheavy-element-117-island-of-stability/ |title=Superheavy Element 117 Points to Fabled "Island of Stability" on Periodic Table |magazine=Scientific American |date= May 7, 2014 |access-date=2014-05-08}}</ref> However, shorter-lived isotopes are usually used in chemical experiments because <sup>266</sup>Lr currently can only be produced as a final [[decay product]] of even heavier and harder-to-make elements: it was discovered in 2014 in the [[decay chain]] of <sup>294</sup>[[tennessine|Ts]].<ref name="Silva1642" /><ref name="266Lr" /> <sup>256</sup>Lr (half-life 27&nbsp;seconds) was used in the first chemical studies on lawrencium: currently, the longer-lived <sup>260</sup>Lr (half-life 2.7&nbsp;minutes) is usually used for this purpose.<ref name="Silva1642" /> After <sup>266</sup>Lr, the longest-lived isotopes are <sup>264</sup>Lr ({{val|4.8|2.2|1.3|u=h}}), <sup>262</sup>Lr (3.6&nbsp;h), and <sup>261</sup>Lr (44&nbsp;min).<ref name="Silva1642" /><ref name="unc">{{Cite web|url=http://www.nucleonica.net/unc.aspx|title=Nucleonica :: Web driven nuclear science}}</ref>{{NUBASE2016|ref}} All other known lawrencium isotopes have half-lives under 5&nbsp;minutes, and the shortest-lived of them (<sup>251</sup>Lr) has a half-life of 24.4&nbsp;milliseconds.<ref name="255Db">{{cite thesis |last1=Leppänen |first1=A.-P. |title=Alpha-decay and decay-tagging studies of heavy elements using the RITU separator |year=2005 |pages=83–100 |publisher=University of Jyväskylä |isbn=978-951-39-3162-9 |issn=0075-465X |url=https://jyx.jyu.fi/bitstream/handle/123456789/13915/978-951-39-3162-9.pdf?sequence=1&isAllowed=y}}</ref><ref name="unc" />{{NUBASE2016|ref}}<ref name=251Lr>{{cite journal |last1=Huang |first1=T. |last2=Seweryniak |first2=D. |last3=Back |first3=B. B. |display-authors=et al. |title=Discovery of the new isotope <sup>251</sup>Lr: Impact of the hexacontetrapole deformation on single-proton orbital energies near the {{nowrap|Z {{=}} 100}} deformed shell gap |journal=Physical Review C |volume=106 |number=L061301 |date=2022 |doi=10.1103/PhysRevC.106.L061301|osti=1906168 |s2cid=254300224 }}</ref> The half-lives of lawrencium isotopes mostly increase smoothly from <sup>251</sup>Lr to <sup>266</sup>Lr, with a dip from <sup>257</sup>Lr to <sup>259</sup>Lr.<ref name="Silva1642" /><ref name="unc" />{{NUBASE2016|ref}}