Europium /(?)/

Eu·ro·pi·um

Europium

n.
  1. A metallic element of the rare-earth group (Lanthanide series), discovered spectroscopically by Demarcay in 1896. Symbol, Eu; atomic number 63; at. wt., 151.965 (C=12.011); valence = +2 or +3. (Chem.)