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: 13.1
Density:       345 g/cm3
Melting Point: 34.53
Boiling Point: 23324