Chemical reactions of the elements

Reaction of promethium with air

I don't think these reactions have ever been done for promethium given the scarcity of promethium. However, one would predict that promethium metal should tarnishe slowly in air and burns readily to form promethium (III) oxide, Pm2O3.

4Pm + 3O2 → 2Pm2O3

Reaction of promethium with water

I don't know if this reaction have ever been done for promethium given the scarcity of promethium. However, one would predict that the silvery white metal promethium is quite electropositive and would react slowly with cold water and quite quickly with hot water to form promethium hydroxide, Pm(OH)3, and hydrogen gas (H2).

2Pm(s) + 6H2O(g) → 2Pm(OH)3(aq) + 3H2(g)

Reaction of promethium with the halogens

I don't think these reactions have ever been done for promethium given the scarcity of promethium. However, one would predict that promethium metal would react with all the halogens to form promethium(III) halides. So, it would react with fluorine, F2, chlorine, Cl2, bromine, I2, and iodine, I2, to form respectively promethium(III) bromide, PmF3, promethium(III) chloride, PmCl3, promethium(III) bromide, PmBr3, and promethium(III) iodide, PmI3.

2Pm(s) + 3F2(g) → 2PmF3(s)

2Pm(s) + 3Cl2(g) → 2PmCl3(s)

2Pm(s) + 3Br2(g) → 2PmBr3(s)

2Pm(s) + 3I2(g) → 2PmI3(s)

Reaction of promethium with acids

Promethium metal dissolves readily in dilute sulphuric acid to form solutions containing the pink aquated Pm(III) ion together with hydrogen gas, H2. It is quite likely that Pm3+(aq) exists as largely the complex ion [Pm(OH2)9]3+

2Pm(s) + 3H2SO4(aq) → 2Pm3+(aq) + 3SO42-(aq) + 3H2(g)

Reaction of promethium with bases

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promethium atomic number