Divalent europium is a mild reducing agent, oxidizing in air to form Eu(III) compounds. The sulfates of both barium and europium(II) are also highly insoluble in water. In terms of size and coordination number, europium(II) and barium(II) are similar. The +2 state has an electron configuration 4 f 7 because the half-filled f-shell provides more stability. This behavior is unusual for most lanthanides, which almost exclusively form compounds with an oxidation state of +3. Europium ignites in air at 150 to 180 ☌ to form europium(III) oxide:Įuropium dissolves readily in dilute sulfuric acid to form pale pink solutions of the hydrated Eu(III), which exist as a nonahydrate: 2 Eu + 3 H 2SO 4 + 18 H 2O → 2 3+ + 3 SO 2−Īlthough usually trivalent, europium readily forms divalent compounds. Its reactivity with water is comparable to that of calcium, and the reaction isīecause of the high reactivity, samples of solid europium rarely have the shiny appearance of the fresh metal, even when coated with a protective layer of mineral oil. It rapidly oxidizes in air, so that bulk oxidation of a centimeter-sized sample occurs within several days. In the divalent state, the strong local magnetic moment (J = 7/ 2) suppresses the superconductivity, which is induced by eliminating this local moment (J = 0 in Eu 3+).Įuropium is the most reactive rare-earth element. If it becomes a superconductor this is believed to occur because europium is divalent in the metallic state, and is converted into the trivalent state by the applied pressure. However the experimental evidence on which this claim is based Įuropium has been claimed to become a superconductor when it is cooled below 1.8 K and compressed to above 80 GPa.

Europium has the second lowest melting point and the lowest density of all lanthanides.

Some properties of europium are strongly influenced by its half-filled electron shell. It crystallizes in a body-centered cubic lattice. Oxidized europium, coated with yellow europium(II) carbonateĮuropium is a ductile metal with a hardness similar to that of lead.

Euiv activator