Atomistry » Actinium
Atomistry »
  Actinium »
    Isotopes »
    Energy »
    Production »
    Application »

Element Actinium, Ac, Actinide or Actinoid

History

Actinium was discovered in 1899 in pitchblende residues by Andre-Louis Debierne, Curie's collaborator. The word actinium comes from the Greek aktis, aktinos, meaning radiant, analogous to the radium (ray). In 1901 Fritz Giesel, investigating the fraction, separated from pitchblende, noted the presence of a new radioactive substance, containing rare-earth elements, which were called emanium. This name also emphasized the radioactive properties (from Lat. emanare meaning emanation). In 1904 it was identified as actinium, after which the latter name was confirmed. Actinum is a member of actinide (or actinoid) group of chemical elements.

Occurrence

10 actinium isotopes with mass numbers from 221 to 230 are known. The most long-lived of them is 227Ac (half-life T1/2 = 21.8 years) which emits β-particles (98.8%) and α-particles (1.2%). Isotopes 227Ac and 228Ac (also called mesothorium, MsThll T1/2 = 6.13 hours) occur in uranium ores as members of natural radioactive series). Earth's crust surface layer 1.6 km deep contains 11 300 metric tons of Actinum-227. However, comparing with other elements actinium abundance is extremely small, 6x10-10% by mass.

Neighbours

Last articles

Zn in 7RE3
Zn in 7RDX
Zn in 7RDZ
Zn in 7RWM
Zn in 7PGU
Zn in 7PGR
Zn in 7PGT
Zn in 7PGS
Zn in 7SQE
Zn in 7RWK
© Copyright 2008-2020 by atomistry.com
Home   |    Site Map   |    Copyright   |    Contact us   |    Privacy