Chemical reactions of the elements
Reaction of thulium with air
Thulium metal tarnishes slowly in air and burns readily to form thulium (III) oxide, Tm2O3.
4Tm + 3O2 → 2Tm2O3
Reaction of thulium with water
The silvery white metal thulium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form thulium hydroxide, Tm(OH)3, and hydrogen gas (H2).
2Tm(s) + 6H2O(g) → 2Tm(OH)3(aq) + 3H2(g)
Reaction of thulium with the halogens
Thulium metal reacts with all the halogens to form thulium(III) halides. So, it reacts with fluorine, F2, chlorine, Cl2, bromine, I2, and iodine, I2, to form respectively thulium(III) bromide, TmF3, thulium(III) chloride, TmCl3, thulium(III) bromide, TmBr3, and thulium(III) iodide, TmI3.
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]
Reaction of thulium with acids
Thulium metal dissolves readily in dilute sulphuric acid to form solutions containing the pale green aquated Tm(III) ion together with hydrogen gas, H2. It is quite likely that Tm3+(aq) exists as largely the complex ion [Tm(OH2)9]3+
2Tm(s) + 3H2SO4(aq) → 2Tm3+(aq) + 3SO42-(aq) + 3H2(g)
Reaction of thulium with bases