It is a chemical element with the symbol Ac and atomic number 89. Element Actinium was first isolated by French chemist André-Louis Debierne in 1899. Friedrich Oskar Giesel later independently isolated it in 1902 and, unaware that it was already known, gave it the name emanium
A soft, silvery-white radioactive metal, actinium reacts rapidly with oxygen and moisture in air forming a white coating of actinium oxide that prevents further oxidation.
A trivalent radioactive element and the prototypical member of the actinide family.
Owing to its strong radioactivity, actinium glows in the dark with a pale blue light, which originates from the surrounding air ionized by the emitted energetic particles
Names and Identifiers
|Molecular Weight:||227.00000 g/mol|
|EC Number :||n/a|
Physical & Chemical Properties
|Boiling Point:||3500±300 K (3200±300 °C|
|Melting Point:||1500 K (1227 °C, 2240 °F)|
Naturally occurring actinium is composed of two radioactive isotopes; 227 Ac (from the radioactive family of 235 U) and 228 Ac (a granddaughter of 232 Th).
227 Ac decays mainly as a beta emitter with a very small energy, but in 1.38% of cases it emits an alpha particle, so it can readily be identified through alpha spectrometry.
|Isotope||Mass/Da||Half-life||Mode of decay||Nuclear spin||Nuclear magnetic moment|
|224Ac||224.021708||2.7 h||β– to 224Th; α to 220Fr; EC to 224Ra||0|
|225Ac||225.02322||10.0 d||α to 221Fr||3/2|
|226Ac||226.026089||1.224 d||β– to 226Th; α to 222Fr; EC to 226Ra||1|
|227Ac||227.027750 (3)||21.77 y||β– to 228Th; α to 224Fr||3/2||1.1|
|228Ac||228.031104||6.15 h||β– to 229Th||3|