Protactinium (Pa)
"The Parent, a rare and expensive hero whose destiny is to decay into Actinium."
A memorable persona to anchor Pa in your mind.
15.37
Grams per cm³
1572
Celsius (°C)
243
Radius (pm)
Daily Life Link
Protactinium has no everyday connection, used only in research.
Discovery & History
Year Discovered
1913
Discovered By
Kasimir Fajans & Oswald Helmuth Göhring
Origin of Name
"The name is derived from the Greek 'protos', meaning first, as a prefix to the element actinium, which is produced through the radioactive decay of proactinium."
Technical Properties
Atomic Mass
231.036 u
Standard State
solid
Boiling Point
4000°C
Electron Configuration
[Rn] 5f26d17s2
1st Ionization Energy
5.89 eV
Electron Affinity
N/A
Oxidation States
"Protactinium is a dense, silvery-gray, highly radioactive metal."
Did You Know?
Its name means "parent of actinium" because it radioactively decays into actinium.
It is one of the rarest and most expensive naturally occurring elements. The UK Atomic Energy Authority once extracted 125 grams of it from 60 tons of nuclear waste at a cost of $500,000.
For a long time after its discovery, it was one of the most difficult elements to study due to its scarcity, high radioactivity, and toxicity.
It is a superconductor at temperatures below 1.4 K.