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Actinium (Ac): Actinides

Actinium (Ac)

What is Actinium?

Actinium (Ac), radioactive chemical element, in Group 3 (IIIb) of the periodic table, atomic number 89. Actinium was discovered (1899) by French chemist André-Louis Debierne in pitchblende residues left after French physicists Pierre and Marie Curie had extracted radium from them, and it was also discovered (1902) independently by German chemist Friedrich Oskar Giesel. Debierne named the element after the Greek word aktinos (“ray”). A ton of pitchblende ore contains about 0.15 mg of actinium. The rare silvery-white metal is highly radioactive, glowing blue in the dark. Continue reading from Encyclopedia Britannica

The History

This element was discovered in 1899 by André Debierne at Paris. He extracted it from the uranium ore pitchblende (uranium oxide, U3O8) in which it occurs in trace amounts. In 1902, Friedrich Otto Giesel independently extracted it from the same mineral and, unaware it was already known, gave it the named emanium.

Actinium extracted from uranium ores is the isotope actinium-227 which has half-life of 21.7 years. It occurs naturally as one of the sequence of isotopes that originate with the radioactive decay of uranium-235. A tonne of pitchblende contains around 150 mg of actinium. Continue reading from Royal Society of Chemistry

Actinium Facts

Actinium is the first of the actinide series of elements. The chemical behavior of actinium is similar to rare earths, especially lanthanum. Actinium is about 150 times as active as radium.

Actinium has 36 isotopes, none of which are stable. Actinium occurs as isotope 227Ac in uranium decay.

Actinium’s high activity level makes it valuable in producing neutrons. There has been some work done to use 225Ac in treating cancer patients.

Isotope 227Ac occurs naturally through the decay of uranium minerals. Actinium metal can been prepared by reducing actinium fluoride with lithium vapor at about 1,100 to 1,300 degrees C (2,012 to 2,372 F). Continue reading from Live Science

Chart of Elemental Properties for Actinium

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