Editing Ytterbium (section)

===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)