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Promethium-Discovery, Properties, And Applications

October 15, 2023
written by Adeel abbas

Promethium is a rare-earth metal and is the only one of its kind that is radioactive. It is considered to be a synthetic element and does not occur naturally in the environment.

image of promethium element
Atomic number61
Relative atomic mass (Ar)Group in the periodic table
Standard stateSolid at 298 K
Period in the periodic table
Group nameLanthanoid
Block in the periodic table6 (lanthanoid)
Block in periodic tablef
Shell structure2.
CAS Registry7440-12-2


Promethium was first discovered in 1945 by American chemists Jacob A. Marinsky, Lawrence E. Glendenin, and Charles D. Coryell. They were working on the fission products of uranium and were able to separate a new radioactive isotope. They named it Promethium after the Greek mythological figure Prometheus.

Physical Properties

Promethium is a silvery-white metal that is malleable and ductile. It has a melting point of 1,042 degrees Celsius and a boiling point of 3,000 degrees Celsius. It is paramagnetic, which means it is weakly attracted to magnetic fields.

Chemical Properties

Promethium is a highly reactive element and readily reacts with air and water. It is considered to be a rare-earth metal, and its chemistry is similar to other rare-earth elements. It can form various oxidation states, including +3, +2, and +1.


  • Promethium is the only rare-earth metal that is radioactive.
  • It has no stable isotopes.
  • Promethium has various applications, including in nuclear batteries, luminous paints, and medical radiation.


Promethium has limited commercial use due to its radioactive nature. However, it has a few applications in different fields. For instance, it is used in nuclear batteries to power spacecraft and satellites. Additionally, it can be used in luminous paints to make glow-in-the-dark items. Furthermore, promethium-147 is used in medicine to treat bone diseases and cancer.