89
Actinium
Atomic Number89
Atomic Mass227 u
CategoryActinide
State at Room TempSolid
Year Discovered1899
About Actinium
Glows an eerie pale blue in the dark as its radiation excites the surrounding air. Named from the Greek aktis, ray, and ancestor of the name actinide for the whole series. Discovered by Andre Debierne in uranium ore. Rarest of the natural actinides and fiercely radioactive, it is used experimentally in targeted alpha therapy for cancer and made in reactors from radium.
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...
90
Thorium
Named after Thor, the Norse god of thunder. Thorium oxide glowed white in gas la...
91
Protactinium
The name means parent of actinium, which it becomes through radioactive decay. O...