Further information Description Great care is required while handling promethium as a consequence of its radioactivity. Promethium salts luminesce in the dark with a pale blue or greenish glow, due to their high radioactivity. Ion-exchange methods led to the preparation of about 10 g of promethium from atomic reactor fuel processing wastes in early 1963. Little is yet generally known about the properties of metallic promethium. More than 30 promethium compounds have been prepared.
Promethium is a rare earth metal.
It appears that there is no known Pm existing in the earth's crust. 33.3 Electronegativities Both values are quoted on the Pauling scale. For most elements, the most stable allotrope is illustrated. This section gives some data for naturally occurring isotopes. Copyright 1997 Mark Winter Department of Chemistry at the University of Sheffield , Sheffield S3 7HF, England.