User:Praseodymium-141/Thulium compounds

Thulium compounds are compounds of the element thulium (Tm). These compounds normally have thulium exhibiting the +3 oxidation state.

Thulium tarnishes slowly in air and burns readily at 150°C to form thulium(III) oxide:
 * 4Tm + 3O2 → 2Tm2O3

Thulium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form thulium hydroxide:
 * 2Tm_{(s)} + 6 H2O_{(l)} → 2Tm(OH)3_{(aq)} + 3H2_{(g)}

Thulium reacts with all the halogens. Reactions are slow at room temperature, but are vigorous above 200°C:
 * 2Tm_{(s)} + 3F2_{(g)} → 2TmF3_{(s)} (white)
 * 2Tm_{(s)} + 3Cl2_{(g)} → 2TmCl3_{(s)} (yellow)
 * 2Tm_{(s)} + 3Br2_{(g)} → 2TmBr3_{(s)} (white)
 * 2Tm_{(s)} + 3I2_{(g)} → 2TmI3_{(s)} (yellow)

Thulium dissolves readily in dilute sulfuric acid to form solutions containing the pale green Tm(III) ions, which exist as [Tm(OH2)9](3+) complexes:
 * 2Tm_{(s)} + 3H2SO4_{(aq)} → 2Tm(3+)_{(aq)} + 3SO4(2-)_{(aq)} + 3H2_{(aq)}

Thulium reacts with various metallic and non-metallic elements forming a range of binary compounds, including TmN, TmS, TmC2, Tm2C3, TmH2, TmH3, TmSi2, TmGe3, TmB4, TmB6 and TmB12. Like most lanthanides, the +3 state is most common and is the only state observed in thulium solutions. Thulium exists as a Tm(3+) ion in solution. In this state, the thulium ion is surrounded by nine molecules of water. Tm(3+) ions exhibit a bright blue luminescence. Because it occurs late in the series, the +2 oxidation state can also exist, stabilized by the nearly full 4f electron shell, but occurs only in solids.

Thulium's only known oxide is Tm2O3. This oxide is sometimes called "thulia". Reddish-purple thulium(II) compounds can be made by the reduction of thulium(III) compounds. Examples of thulium(II) compounds include the halides (except the fluoride). Some hydrated thulium compounds, such as TmCl3*7H2O and Tm2(C2O4)3*6H2O are green or greenish-white. Thulium dichloride reacts very vigorously with water. This reaction results in hydrogen gas and Tm(OH)3 exhibiting a fading reddish color. Combination of thulium and chalcogens results in thulium chalcogenides.

Thulium reacts with hydrogen chloride to produce hydrogen gas and thulium chloride. With nitric acid it yields thulium nitrate, or Tm(NO3)3.