Editing Ytterbium (section)

==Characteristics==

===Physical properties===
Ytterbium is a soft, [[malleability|malleable]] and [[ductility|ductile]] [[chemical element]]. When freshly prepared, it is less golden than cesium. It is a [[rare-earth element]], and it is readily dissolved by the strong [[mineral acid]]s. <ref name="CRC">{{cite book| author = Hammond, C. R. |title = The Elements, in Handbook of Chemistry and Physics |edition = 81st| publisher =CRC press| date = 2000| isbn = 978-0-8493-0481-1}}</ref>

Ytterbium has three [[Allotropy|allotropes]] labeled by the Greek letters alpha, beta and gamma. Their transformation temperatures are −13&nbsp;°[[Celsius|C]] and 795&nbsp;°C,<ref name="CRC" /> although the exact transformation temperature depends on the [[pressure]] and [[stress (mechanics)|stress]].<ref name="alpha-Yb" /> The beta allotrope (6.966&nbsp;g/cm<sup>3</sup>) exists at room temperature, and it has a [[face-centered cubic]] [[crystal structure]]. The high-temperature gamma allotrope (6.57&nbsp;g/cm<sup>3</sup>) has a [[body-centered cubic]] crystalline structure.<ref name="CRC" /> The alpha allotrope (6.903&nbsp;g/cm<sup>3</sup>) has a [[hexagonal crystal system|hexagonal]] crystalline structure and is stable at low temperatures.<ref name="Holl" /> 

The beta allotrope has a metallic [[electrical conductivity]] at normal atmospheric pressure, but it becomes a [[semiconductor]] when exposed to a pressure of about 16,000 [[atmospheric pressure|atmospheres]] (1.6&nbsp;[[gigapascal|GPa]]). Its electrical [[resistivity]] increases ten times upon compression to 39,000 atmospheres (3.9&nbsp;GPa), but then drops to about 10% of its room-temperature resistivity at about 40,000&nbsp;atm (4.0&nbsp;GPa).<ref name="CRC" /><ref name="history" />

In contrast to the other rare-earth metals, which usually have [[antiferromagnetic]] and/or [[ferromagnetic]] properties at low [[temperature]]s, ytterbium is [[paramagnetic]] at temperatures above 1.0 [[kelvin]].<ref>Jackson, M. (2000). [http://www.irm.umn.edu/quarterly/irmq10-3.pdf "Magnetism of Rare Earth"]. The IRM quarterly 10(3): 1</ref> However, the alpha allotrope is [[diamagnetic]].<ref name="alpha-Yb">{{Cite journal | last1 = Bucher | first1 = E. | last2 = Schmidt | first2 = P. | last3 = Jayaraman | first3 = A. | last4 = Andres | first4 = K. | last5 = Maita | first5 = J. | last6 = Nassau | first6 = K. | last7 = Dernier | first7 = P. | doi = 10.1103/PhysRevB.2.3911 | title = New First-Order Phase Transition in High-Purity Ytterbium Metal | journal = Physical Review B | volume = 2 | issue = 10 | pages = 3911 | year = 1970 |bibcode = 1970PhRvB...2.3911B }}</ref> With a [[melting point]] of 824&nbsp;°C and a [[boiling point]] of 1196&nbsp;°C, ytterbium has the smallest liquid range of all the metals.<ref name="CRC" />

Contrary to most other lanthanides, which have a close-packed hexagonal lattice, ytterbium crystallizes in the face-centered cubic system. Ytterbium has a density of 6.973&nbsp;g/cm<sup>3</sup>, which is significantly lower than those of the neighboring lanthanides, [[thulium]] (9.32&nbsp;g/cm<sup>3</sup>) and [[lutetium]] (9.841&nbsp;g/cm<sup>3</sup>). Its melting and boiling points are also significantly lower than those of thulium and lutetium. This is due to the closed-shell electron configuration of ytterbium ([Xe] 4f<sup>14</sup> 6s<sup>2</sup>), which causes only the two 6s electrons to be available for [[metallic bonding]] (in contrast to the other lanthanides where three electrons are available) and increases ytterbium's [[metallic radius]].<ref name="Holl" />

===Chemical properties===
Ytterbium metal tarnishes slowly in air, taking on a golden or brown hue. Finely dispersed ytterbium readily oxidizes in air and under oxygen. Mixtures of powdered ytterbium with [[polytetrafluoroethylene]] or [[hexachloroethane]] burn with an emerald-green flame.<ref>{{Cite journal | last1 = Koch | first1 = E. C. | last2 = Weiser | first2 = V. | last3 = Roth | first3 = E. | last4 = Knapp | first4 = S. | last5 = Kelzenberg | first5 = S. | title = Combustion of Ytterbium Metal | doi = 10.1002/prep.201100141 | journal = Propellants, Explosives, Pyrotechnics | volume = 37 | pages = 9–11 | year = 2012 }}</ref> Ytterbium reacts with [[hydrogen]] to form various [[non-stoichiometric compound|non-stoichiometric]] [[hydride]]s. Ytterbium dissolves slowly in water, but quickly in acids, liberating hydrogen.<ref name="Holl" />

Ytterbium is quite [[electropositive]], and it reacts slowly with cold water and quite quickly with hot water to form ytterbium(III) hydroxide:<ref name="webelements" />
:2 Yb (s) + 6 H<sub>2</sub>O (l) → 2 Yb(OH)<sub>3</sub> (aq) + 3 H<sub>2</sub> (g)

Ytterbium reacts with all the [[halogen]]s:<ref name="webelements" />
:2 Yb (s) + 3 F<sub>2</sub> (g) → 2 YbF<sub>3</sub> (s) [white]
:2 Yb (s) + 3 Cl<sub>2</sub> (g) → 2 YbCl<sub>3</sub> (s) [white]
:2 Yb (s) + 3 Br<sub>2</sub> (l) → 2 YbBr<sub>3</sub> (s) [white]
:2 Yb (s) + 3 I<sub>2</sub> (s) → 2 YbI<sub>3</sub> (s) [white]

The ytterbium(III) ion absorbs light in the [[near-infrared]] range of wavelengths, but not in [[visible light]], so [[ytterbia]], Yb<sub>2</sub>O<sub>3</sub>, is white in color and the salts of ytterbium are also colorless. Ytterbium dissolves readily in dilute [[sulfuric acid]] to form solutions that contain the colorless Yb(III) ions, which exist as nonahydrate complexes:<ref name="webelements">{{cite web| url =https://www.webelements.com/ytterbium/chemistry.html| title =Chemical reactions of Ytterbium| publisher=Webelements| access-date=2009-06-06}}</ref>

:2 Yb (s) + 3 H<sub>2</sub>SO<sub>4</sub> (aq) + 18 {{chem|H|2|O}} (l) → 2 [Yb(H<sub>2</sub>O)<sub>9</sub>]<sup>3+</sup> (aq) + 3 {{chem|SO|4|2-}} (aq) + 3 H<sub>2</sub> (g)

===Yb(II) vs. Yb(III)===
Although usually trivalent, ytterbium readily forms divalent compounds. This behavior is unusual for [[lanthanide]]s, which almost exclusively form compounds with an oxidation state of +3. The +2 state has a valence [[electron configuration]] of 4''f''<sup>14</sup> because the fully filled ''f''-shell gives more stability. The yellow-green ytterbium(II) ion is a very strong [[reducing agent]] and decomposes water, releasing [[hydrogen]], and thus only the colorless ytterbium(III) ion occurs in [[aqueous solution]]. [[Samarium]] and [[thulium]] also behave this way in the +2 state, but [[europium]](II) is stable in aqueous solution. Ytterbium metal behaves similarly to europium metal and the alkaline earth metals, dissolving in ammonia to form blue [[electride]] salts.<ref name="Holl" />

===Isotopes===
{{Main|Isotopes of ytterbium}}
Natural ytterbium is composed of seven stable [[isotope]]s: <sup>168</sup>Yb, <sup>170</sup>Yb, <sup>171</sup>Yb, <sup>172</sup>Yb, <sup>173</sup>Yb, <sup>174</sup>Yb, and <sup>176</sup>Yb, with <sup>174</sup>Yb being the most common, at 31.8% of the [[natural abundance]]). Thirty-two [[radioisotope]]s have been observed, with the most stable ones being <sup>169</sup>Yb with a [[half-life]] of 32.0 days, <sup>175</sup>Yb with a half-life of 4.18 days, and <sup>166</sup>Yb with a half-life of 56.7 hours. All of the remaining [[radioactive]] isotopes have half-lives that are less than two hours, and most of these have half-lives under 20 minutes. Ytterbium also has 12 [[meta state]]s, with the most stable being <sup>169m</sup>Yb (''t''<sub>1/2</sub> 46 seconds).<ref name="nucleonica">{{cite web |url=http://www.nucleonica.net/unc.aspx |title=Nucleonica: Universal Nuclide Chart |date=2007–2011 |publisher=Nucleonica |access-date=July 22, 2011}}</ref>{{NUBASE2020|ref}}

The isotopes of ytterbium range from <sup>149</sup>Yb to <sup>187</sup>Yb.{{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 primary [[decay mode]] of ytterbium isotopes lighter than the most abundant stable isotope, <sup>174</sup>Yb, is [[electron capture]], and the primary decay mode for those heavier than <sup>174</sup>Yb is [[beta decay]]. The primary [[decay product]]s of ytterbium isotopes lighter than <sup>174</sup>Yb are [[thulium]] isotopes, and the primary decay products of ytterbium isotopes with heavier than <sup>174</sup>Yb are [[lutetium]] isotopes.<ref name="nucleonica" />{{NUBASE2020|ref}}