91
Protactinium
Atomic Number91
Atomic Mass231.0 u
CategoryActinide
State at Room TempSolid
Year Discovered1913
About Protactinium
The name means parent of actinium, which it becomes through radioactive decay. One of the rarest and most inaccessible natural elements: extracting a gram once required 60 tonnes of waste ore. Scarce, fiercely radioactive, and with no uses outside research, though its decay helps date marine sediments millions of years old. Isolated in pure form only in 1934.
More Actinides
92
Uranium
The heaviest naturally abundant element. Named after the planet Uranus. Enriched...
94
Plutonium
Named after the dwarf planet Pluto, following the uranium-neptunium-plutonium se...
89
Actinium
Glows an eerie pale blue in the dark as its radiation excites the surrounding ai...
90
Thorium
Named after Thor, the Norse god of thunder. Thorium oxide glowed white in gas la...