Promethium (Pm)

NUM: 61
SYMBOL: Pm
CATEGORY: Lanthanide

Promethium is a radioactive lanthanide; all its isotopes are radioactive and extremely rare in nature.

Promethium was conclusively identified in 1945 at Oak Ridge by Marinsky, Glendenin, and Coryell among uranium fission products.
It has no stable isotopes, and only about half a kilogram exists naturally in Earth's crust at any moment.
Promethium-147 powers luminous paints that replaced radium and compact nuclear batteries for spacecraft and instruments.