Promethium (Pm)
"The Stolen Fire, a synthetic hero who provides long-lasting power in the darkest places."
A memorable persona to anchor Pm in your mind.
7.26
Grams per cm³
1042
Celsius (°C)
236
Radius (pm)
Daily Life Link
Promethium is found in the luminous paint on old watch dials.
Discovery & History
Year Discovered
1945
Discovered By
Jacob A. Marinsky, Lawrence E. Glendenin & Charles D. Coryell
Origin of Name
"Promethium is named after Prometheus of Greek mythology who stole fire from the Gods and gave it to humans."
Technical Properties
Atomic Mass
[145] u
Standard State
solid
Boiling Point
3000°C
Electron Configuration
[Xe] 4f56s2
1st Ionization Energy
5.55 eV
Electron Affinity
N/A
Oxidation States
"Promethium is a radioactive, metallic element."
Did You Know?
It is named after the Titan Prometheus from Greek mythology, who stole fire from the gods and gave it to humans.
It is the second-to-last naturally occurring rare-earth element to be discovered because all of its isotopes are radioactive and it is extremely rare.
Tiny amounts of promethium can be used to make atomic batteries, where the radioactive decay is converted into electricity to power devices like pacemakers or spacecraft for many years.
It was once used in luminous paint for watch dials, but this has been discontinued due to concerns about radiation.