A silvery-white, radioactive, metallic element and first member of the actinide series;
it is also a transition element in group IIIB of the periodic table.
Actinium was discovered by Andre Debierne in 1899 and is found associated
with ores of uranium; however, it is difficult
to separate and is best prepared by bombardment of radium with neutrons. It is separated from other
species by ion exchange or solvent extraction. Its most stable isotope, 227Ac, with a half-life of
21.8 years, is a decay product of uranium-235. Actinium glows blue and is
oxidized in air.
|Electron configuration of
Very few actinium compounds have been isolated because of the element's
intense radioactivity. In its compounds actinium is tripositive, forming
very similar compounds to lanthanum. Actinium
salts are colorless.
|relative atomic mass