Editing Lutetium (section)

==Characteristics==
===Physical properties===
A lutetium atom has 71 electrons, arranged in the [[electron configuration|configuration]] &#91;[[xenon|Xe]]&#93;&nbsp;4f<sup>14</sup>5d<sup>1</sup>6s<sup>2</sup>.<ref name="Cotton">{{Greenwood&Earnshaw|page=1223}}</ref> Lutetium is generally encountered in the +3 oxidation state, having lost its two outermost 6s and the single 5d-electron. The lutetium atom is the smallest among the lanthanide atoms, due to the [[lanthanide contraction]],<ref>{{Cotton&Wilkinson5th|pages=776, 955}}</ref> and as a result lutetium has the highest density, melting point, and hardness of the lanthanides.<ref name="Parker">{{cite book| last=Parker | first= Sybil P.| title =Dictionary of Scientific and Technical Terms| edition =3rd| location = New York| publisher = McGraw-Hill| date = 1984}}</ref> As lutetium's 4f orbitals are highly stabilized only the 5d and 6s orbitals are involved in chemical reactions and bonding;<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.|author-link=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><ref>{{cite journal | last1=Krinsky | first1=Jamin L. | last2=Minasian | first2=Stefan G. | last3=Arnold | first3=John | title=Covalent Lanthanide Chemistry Near the Limit of Weak Bonding: Observation of (CpSiMe<sub>3</sub>)<sub>3</sub>Ce−ECp* and a Comprehensive Density Functional Theory Analysis of Cp<sub>3</sub>Ln−ECp (E = Al, Ga) | journal=Inorganic Chemistry | publisher=American Chemical Society (ACS) | volume=50 | issue=1 | date=2010-12-08 | issn=0020-1669 | doi=10.1021/ic102028d | pages=345–357| pmid=21141834 }}</ref> thus it is characterized as a d-block rather than an f-block 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 |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> and on this basis some consider it not to be a lanthanide at all, but a [[transition metal]] like its lighter congeners [[scandium]] and [[yttrium]].<ref>{{cite web |url=https://www.webelements.com/ |title=WebElements |last=Winter |first=Mark |date=1993–2022 |publisher=The University of Sheffield and WebElements Ltd, UK |access-date=5 December 2022 }}</ref><ref>{{cite book |last=Cowan |first=Robert D. |date=1981 |title=The Theory of Atomic Structure and Spectra |publisher=University of California Press |page=598 |isbn=978-0-520-90615-0}}</ref>

===Chemical properties and compounds===
{{category see also|Lutetium compounds}}
Lutetium's compounds almost always contain the element in the +3 oxidation state.<ref>{{cite web|url=https://www.britannica.com/science/lutetium|title=Lutetium}}</ref> Aqueous solutions of most lutetium salts are colorless and form white crystalline solids upon drying, with the common exception of the iodide, which is brown. The soluble salts, such as nitrate, sulfate and acetate form hydrates upon crystallization. The [[lutetium(III) oxide|oxide]], hydroxide, fluoride, carbonate, phosphate and [[oxalate]] are insoluble in water.<ref name="patnaik" />

Lutetium metal is slightly unstable in air at standard conditions, but it burns readily at 150&nbsp;°C to form lutetium oxide. The resulting compound is known to absorb water and [[carbon dioxide]], and it may be used to remove vapors of these compounds from closed atmospheres.<ref name="aaaaaa">{{cite book| pages = [https://archive.org/details/historyuseourear00kreb_356/page/n327 303]–304| title = The history and use of our earth's chemical elements: a reference guide | url = https://archive.org/details/historyuseourear00kreb_356| url-access = limited| last= Krebs| first= Robert E.| publisher =Greenwood Publishing Group| date = 2006| isbn =978-0-313-33438-2}}</ref> Similar observations are made during reaction between lutetium and water (slow when cold and fast when hot); lutetium hydroxide is formed in the reaction.<ref name="ffff">{{cite web| url =https://www.webelements.com/lutetium/chemistry.html| title =Chemical reactions of Lutetium| publisher=Webelements| access-date=2009-06-06}}</ref> Lutetium metal is known to react with the four lightest halogens to form [[halides|trihalides]]; except the fluoride they are soluble in water. {{Citation needed|date=December 2024}}

Lutetium dissolves readily in weak acids<ref name="aaaaaa" /> and dilute [[sulfuric acid]] to form solutions containing the colorless lutetium ions, which are coordinated by between seven and nine water molecules, the average being {{chem2|[Lu(H2O)8.2](3+)}}.<ref name="Persson2010">{{cite journal|last1=Persson|first1=Ingmar|title=Hydrated metal ions in aqueous solution: How regular are their structures?|journal=Pure and Applied Chemistry|volume=82|issue=10|date=2010|pages=1901–1917|issn=0033-4545|doi=10.1351/PAC-CON-09-10-22|doi-access=free}}</ref>

:{{chem2|2 Lu + 3 H2SO4 → 2 Lu(3+) + 3 SO4(2-) + 3 H2↑}}

===Oxidation states===

Lutetium is usually found in the +3 oxidation state, like most other lanthanides. However, it can also be in the 0, +1 and +2 states as well.
===Isotopes===
{{main|Isotopes of lutetium}}
Lutetium occurs on the Earth in form of two isotopes: lutetium-175 and lutetium-176. Out of these two, only the former is stable, making the element [[monoisotopic element|monoisotopic]]. The latter one, lutetium-176, decays via [[beta decay]] with a [[half-life]] of {{val|3.78|e=10|u=years}}; it makes up about 2.5% of natural lutetium.{{NUBASE2020|ref}}
To date, 40 [[synthetic radioisotope]]s of the element have been characterized, ranging in [[mass number]] from 149 to 190;{{NUBASE2020|ref}}<ref name=PRL132.7>{{cite journal |first1=O. B. |last1=Tarasov |first2=A. |last2=Gade |first3=K. |last3=Fukushima |display-authors=et al. |title=Observation of New Isotopes in the Fragmentation of <sup>198</sup>Pt at FRIB |journal=Physical Review Letters |volume=132 |number=72501 |date=2024 |page=072501 |doi=10.1103/PhysRevLett.132.072501|pmid=38427880 |bibcode=2024PhRvL.132g2501T }}</ref> the most stable such isotopes are lutetium-174 with a half-life of 3.31 years, and lutetium-173 with a half-life of 1.37 years.{{NUBASE2020|ref}} All of the remaining [[Radioactive decay|radioactive]] isotopes have half-lives that are less than 9 days, and the majority of these have half-lives that are less than half an hour.{{NUBASE2020|ref}} Isotopes lighter than the stable lutetium-175 decay via [[electron capture]] (to produce isotopes of [[ytterbium]]), with some [[alpha emission|alpha]] and [[positron emission]]; the heavier isotopes decay primarily via beta decay, producing hafnium isotopes.{{NUBASE2020|ref}}

The element also has 43 known [[nuclear isomer]]s, with masses of 150, 151, 153–162, and 166–180 (not every mass number corresponds to only one isomer). The most stable of them are lutetium-177m, with a half-life of 160.4 days, and lutetium-174m, with a half-life of 142 days; these are longer than the half-lives of the ground states of all radioactive lutetium isotopes except lutetium-173, 174, and 176.{{NUBASE2020|ref}}