Editing Erbium (section)

== Characteristics ==

===Physical properties===
[[Image:Erbium(III)chloride sunlight.jpg|thumb|left|Erbium(III) chloride in sunlight, showing some pink fluorescence of Er<sup>+3</sup> from natural ultraviolet.]]
A [[valence (chemistry)|trivalent]] element, pure erbium [[metal]] is malleable (or easily shaped), soft yet stable in air, and does not [[oxidation|oxidize]] as quickly as some other [[rare-earth metals]]. Its [[Salt (chemistry)|salts]] are rose-colored, and the element has characteristic sharp [[absorption spectra]] bands in [[visible light]], [[ultraviolet]], and near [[infrared]].<ref>{{Cite journal |last1=Humpidge |first1=J. S. |last2=Burney |first2=W. |date=1879-01-01 |title=XIV.—On erbium and yttrium |url=https://pubs.rsc.org/en/content/articlelanding/1879/ct/ct8793500111 |journal=Journal of the Chemical Society, Transactions |language=en |volume=35 |pages=111–117 |doi=10.1039/CT8793500111 |issn=0368-1645}}</ref> Otherwise it looks much like the other rare earths. Its [[sesquioxide]] is called [[erbia]]. Erbium's properties are to a degree dictated by the kind and amount of impurities present. Erbium does not play any known biological role, but is thought to be able to stimulate [[metabolism]].<ref name="emsley">{{cite book | title = Nature's Building Blocks: An A-Z Guide to the Elements | last = Emsley | first = John | publisher = Oxford University Press | date = 2001 | location = Oxford, England, UK | isbn = 978-0-19-850340-8 | chapter = Erbium | pages = [https://archive.org/details/naturesbuildingb0000emsl/page/136 136–139] | chapter-url = https://books.google.com/books?id=j-Xu07p3cKwC | url = https://archive.org/details/naturesbuildingb0000emsl/page/136 }}</ref>

Erbium is [[Ferromagnetism|ferromagnetic]] below 19&nbsp;K, [[Antiferromagnetism|antiferromagnetic]] between 19 and 80 K and [[Paramagnetism|paramagnetic]] above 80&nbsp;K.<ref>{{cite journal| author = Jackson, M.| title = Magnetism of Rare Earth| url = http://www.irm.umn.edu/quarterly/irmq10-3.pdf| journal = The IRM Quarterly| volume = 10| issue = 3| page = 1| date = 2000| access-date = 2009-05-03| archive-url = https://web.archive.org/web/20170712151422/http://www.irm.umn.edu/quarterly/irmq10-3.pdf| archive-date = 2017-07-12| url-status = dead}}</ref>

Erbium can form propeller-shaped atomic clusters Er<sub>3</sub>N, where the distance between the erbium atoms is 0.35&nbsp;nm. Those clusters can be isolated by encapsulating them into [[fullerene]] molecules, as confirmed by [[transmission electron microscopy]].<ref>{{cite journal| title = Structures of ''D''<sub>5</sub>''<sub>d</sub>''-C<sub>80</sub> and ''I''<sub>h</sub>''-Er''<sub>3</sub>N@C<sub>80</sub> Fullerenes and Their Rotation Inside Carbon Nanotubes Demonstrated by Aberration-Corrected Electron Microscopy| date = 2007| journal = Nano Letters| volume = 7| page = 3704|bibcode = 2007NanoL...7.3704S| issue = 12 |doi =10.1021/nl0720152|last1 = Sato|first1 = Yuta| last2 = Suenaga| first2 = Kazu| last3 = Okubo| first3 = Shingo| last4 = Okazaki| first4 = Toshiya| last5 = Iijima| first5 = Sumio}}</ref>

Like most [[rare-earth elements]], erbium is usually found in the +3 oxidation state. However, it is possible for erbium to also be found in the 0, +1 and +2<ref>{{Cite journal |last1=MacDonald |first1=Matthew R. |last2=Bates |first2=Jefferson E. |last3=Fieser |first3=Megan E. |last4=Ziller |first4=Joseph W. |last5=Furche |first5=Filipp |last6=Evans |first6=William J. |date=2012-05-23 |title=Expanding Rare-Earth Oxidation State Chemistry to Molecular Complexes of Holmium(II) and Erbium(II) |url=https://pubs.acs.org/doi/10.1021/ja303357w |journal=Journal of the American Chemical Society |language=en |volume=134 |issue=20 |pages=8420–8423 |doi=10.1021/ja303357w |pmid=22583320 |bibcode=2012JAChS.134.8420M |issn=0002-7863|url-access=subscription }}</ref> oxidation states.

===Chemical properties===
Erbium metal retains its luster in dry air, however will tarnish slowly in moist air and burns readily to form [[erbium(III) oxide]]:<ref name="emsley" />
:4 Er + 3 O<sub>2</sub> → 2 Er<sub>2</sub>O<sub>3</sub>

Erbium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form [[erbium hydroxide]]:<ref>{{cite journal | url=https://iopscience.iop.org/article/10.1088/0957-4484/19/18/185606/meta | doi=10.1088/0957-4484/19/18/185606 | title=Synthesis of erbium hydroxide microflowers and nanostructures in subcritical water | year=2008 | last1=Assaaoudi | first1=H. | last2=Fang | first2=Z. | last3=Butler | first3=I. S. | last4=Kozinski | first4=J. A. | journal=Nanotechnology | volume=19 | issue=18 | page=185606 | pmid=21825694 | bibcode=2008Nanot..19r5606A | s2cid=24755693 | url-access=subscription }}</ref>
:2 Er (s) + 6 H<sub>2</sub>O (l) → 2 Er(OH)<sub>3</sub> (aq) + 3 H<sub>2</sub> (g)

Erbium metal reacts with all the halogens:<ref name="Webelements" />
:2 Er (s) + 3 F<sub>2</sub> (g) → 2 ErF<sub>3</sub> (s) [pink]
:2 Er (s) + 3 Cl<sub>2</sub> (g) → 2 ErCl<sub>3</sub> (s) [violet]
:2 Er (s) + 3 Br<sub>2</sub> (g) → 2 ErBr<sub>3</sub> (s) [violet]
:2 Er (s) + 3 I<sub>2</sub> (g) → 2 ErI<sub>3</sub> (s) [violet]

Erbium dissolves readily in dilute [[sulfuric acid]] to form solutions containing hydrated Er(III) ions, which exist as rose red [Er(OH<sub>2</sub>)<sub>9</sub>]<sup>3+</sup> hydration complexes:<ref name="Webelements">{{cite web| url =https://www.webelements.com/erbium/chemistry.html| title =Chemical reactions of Erbium| publisher=Webelements| access-date=2009-06-06}}</ref>

:2 Er (s) + 3 H<sub>2</sub>SO<sub>4</sub> (aq) → 2 Er<sup>3+</sup> (aq) + 3 {{chem|SO|4|2-}} (aq) + 3 H<sub>2</sub> (g)

=== Isotopes ===
{{main|Isotopes of erbium}}
Naturally occurring erbium is composed of 6 stable [[isotope]]s, {{Sup|162}}Er, {{Sup|164}}Er, {{Sup|166}}Er, {{Sup|167}}Er, {{Sup|168}}Er, and {{Sup|170}}Er, with {{Sup|166}}Er being the most abundant (33.503% [[natural abundance]]). 32 [[radioisotope]]s have been characterized, with the most stable being {{Sup|169}}Er with a [[half-life]] of {{val|9.392|u=days}}, {{Sup|172}}Er with a half-life of {{val|49.3|u=hours}}, {{Sup|160}}Er with a half-life of {{val|28.58|u=hours}}, {{Sup|165}}Er with a half-life of {{val|10.36|u=hours}}, and {{Sup|171}}Er with a half-life of {{val|7.516|u=hours}}. All of the remaining [[radioactive]] isotopes have half-lives that are less than {{val|3.5|u=hours}}, and the majority of these have half-lives that are less than 4 minutes. This element also has 26 [[meta state]]s, with the most stable being {{Sup|149m}}Er with a half-life of {{val|8.9|u=seconds}}.{{NUBASE2020|ref}}

The isotopes of erbium range in {{Sup|143}}Er to {{Sup|180}}Er. The primary [[decay mode]] before the most abundant stable isotope, {{Sup|166}}Er, is [[electron capture]], and the primary mode after is [[beta decay]]. The primary [[decay product]]s before {{Sup|166}}Er are element 67 ([[holmium]]) isotopes, and the primary products after are element 69 ([[thulium]]) isotopes.{{NUBASE2020|ref}}

{{Sup|165}}Er has been identified as useful for use in [[Auger therapy]], as it decays via electron capture and emits no [[Gamma ray|gamma radiation]]. It can also be used as a [[radioactive tracer]] to label [[Antibody|antibodies]] and [[Peptide|peptides]], though it cannot be detected by any kind of imaging for the study of its biological distribution. The isotope can be produced via the bombardment of {{Sup|166}}Er with {{Sup|165}}[[Thulium|Tm]] or {{Sup|165}}Er with {{Sup|165}}[[Holmium|Ho]], the latter of which is more convenient due to {{Sup|165}}Ho being a stable [[primordial isotope]], though it requires an initial supply of {{Sup|165}}Er.<ref>{{Cite book |last=IAEA |title=Alternative Radionuclide Production with a Cyclotron |date=2021 |isbn=9789201032218 |chapter=4.11. Erbium-165 |publisher=International Atomic Energy Agency |oclc=1317842424}}</ref>