A radioactive element. The name derives from the Greek, aktis or akinis for "beam or ray" because it is a powerful source of alpha radiation. A soft silvery-white radioactive metallic element that is the first member of the actinoid series. It occurs in minute quantities in uranium ores. It can be produced by neutron bombardment of radium. The metal glows in the dark.


Discovered by the French chemist Andre-Louis Debierne in 1899 and independently discovered by German chemist Friedrich Oskar Giesel in 1902, who called it emanium.

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Atomic number 89 Clip
Atomic / Molecular Weight 227.0278 gmol-1Clip
Density 10060 kgm-3Clip
Crystal Structure fcc Clip
Lattice constant 531 fmClip
Melting Point 1503 KClip
Boiling Point 3473 KClip
Stability Unstable Clip
Half Life 686538720 sClip
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See also: Periodic Table.

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Subjects: Chemistry