Chemical reactions of the elements

Reaction of thallium with air

Freshy cut thallium tarnishes slowly to give a grey oxide film that protects the remaining metal from further oxidation. When heated strongly to red heat in air, poisonous thallium(I) oxide is formed.

2Tl(s) + O2(g) → Tl2O(s)

Reaction of thallium with water

Thallium seems not to react with air-free water. Thallium metal tarnishes slowly in moist air or dissolves in water to give poisonous thallium(I) hydroxide.

2Tl(s) + 2H2O(l) → 2TlOH(aq) + H2(g)

Reaction of thallium with the halogens

Thallium metal reacts vigorously with fluorine, F2, chlorine, Cl2, and bromine, Br2, to form the dihalides thallium(III) fluoride, TlF3, thallium(III) chloride, TlCl3, tand hallium(III) bromide, TlBr3, respectively. All these compounds are poisonous.

2Tl(s) + 3F2(g) → 2TlF3(s) []

2Tl(s) + 3Cl2(g) → 2TlCl3(s) []

2Tl(s) + 3Br2(l) → 2TlBr3(s) []

Reaction of thallium with acids

Thallium dissolves only slowly in sulphuric acid, H2SO4, or hydrochloric acid, HCl, because the poisonous thallium(I) salts produced are not very soluble.

Reaction of thallium with bases

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thallium atomic number