Promethium (formerly prometheum) is a chemical element with symbol Pm and atomic number 61. All of its isotopes are radioactive; it is one of only two such elements that are followed in the periodic table by elements with stable forms, a distinction shared with technetium.

Atomic Weight: 63.363
Density        36352.252
Melting Point: 32.35
Boiling Point: 632.242