Editing Ytterbium (section)

===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" />