Chemical reactions of the elements
Reaction of erbium with air
Erbium metal tarnishes slowly in air and burns readily to form erbium (III) oxide, Er2O3.
4Er + 3O2 → 2Er2O3
Reaction of erbium with water
The silvery white metal erbium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form erbium hydroxide, Er(OH)3, and hydrogen gas (H2).
2Er(s) + 6H2O(g) → 2Er(OH)3(aq) + 3H2(g)
Reaction of erbium with the halogens
Erbium metal reacts with all the halogens to form erbium(III) halides. So, it reacts with fluorine, F2, chlorine, Cl2, bromine, I2, and iodine, I2, to form respectively erbium(III) bromide, ErF3, erbium(III) chloride, ErCl3, erbium(III) bromide, ErBr3, and erbium(III) iodide, ErI3.
2Er(s) + 3F2(g) → 2ErF3(s) [pink]
2Er(s) + 3Cl2(g) → 2ErCl3(s) [violet]
2Er(s) + 3Br2(g) → 2ErBr3(s) [violet]
2Er(s) + 3I2(g) → 2ErI3(s) [violet]
Reaction of erbium with acids
Erbium metal dissolves readily in dilute sulphuric acid to form solutions containing the yellow aquated Er(III) ion together with hydrogen gas, H2. It is quite likely that Er3+(aq) exists as largely the complex ion [Er(OH2)9]3+
2Er(s) + 3H2SO4(aq) → 2Er3+(aq) + 3SO42-(aq) + 3H2(g)
Reaction of erbium with bases