A radioactive lanthanide element with the symbol Pm and atomic number 61. It is one of the rarest and most expensive elements in the periodic table, with only about 500–600 grams naturally occurring in Earth’s crust at any given time. It is produced by the decay of uranium or europium, and has one stable isotope (147 Pm) with applications in luminous paint, atomic batteries and thickness-measurement devices.

All promethium isotopes are radioactive.

Promethium is paramagnetic.

Promethium is not flammbale.

Promethium bromide contain promethium and bromine.