Reaction of terbium with acids
Terbium dissolves readily in dilute sulphuric acid, forming a very pale pink solution of Tb(III) ions and hydrogen gas, H2.
2 Tb(s) + 3 H2SO4(aq) 2 Tb3+(aq) + 3 SO42−(aq) + 3 H2(g)
Reaction of terbium with air
Terbium tarnishes slowly in air and burns readily, forming terbium oxides (no reference to composition yet).
Reaction of terbium with halogens
Terbium reacts with the halogens, forming the corresponding terbium(III) halides:
2 Tb(s) + 3 F2(g) 2 TbF3(s) [white]
2 Tb(s) + 3 Cl2(g) 2 TbCl3(s) [white]
2 Tb(s) + 3 Br2(g) 2 TbBr3(s) [white]
2 Tb(s) + 3 I2(g) 2 TbI3(s) [yellow]
Reaction of terbium with water
Terbium reacts slowly with cold water, and quickly with hot water, forming terbium(III) hydroxide, Tb(OH)3, and hydrogen gas, H2
2 Tb(s) + 6 H2O(l) 2 Tb(OH)3(aq) + 3 H2(g)