Europium vs. Promethium

Europiumnoun

A metallic chemical element (symbol Eu) with an atomic number of 63.

Promethiumnoun

A metallic chemical element (symbol Pm) with an atomic number of 61.

Europiumnoun

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.

Promethiumnoun

a soft silvery metallic element of the rare earth group having no stable isotope; was discovered in radioactive form as a fission product of uranium

Europiumnoun

a bivalent and trivalent metallic element of the rare earth group

Promethium

Promethium is a chemical element with the symbol Pm and atomic number 61. All of its isotopes are radioactive; it is extremely rare, with only about 500–600 grams naturally occurring in Earth's crust at any given time.

Europium

Europium is a chemical element with the symbol Eu and atomic number 63. Europium is the most reactive lanthanide by far, having to be stored under an inert fluid to protect it from atmospheric oxygen or moisture.