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Actinium is a chemical element; it has symbol Ac and atomic number 89. ... André-Louis Debierne, a French chemist, announced the discovery of a new element in 1899.
In 1899, he discovered the radioactive element actinium, as a result of continuing the work with pitchblende that the Curies had initiated. After the death of Pierre Curie in 1906, Debierne helped Marie Curie carry on and worked with her in teaching and research. In 1911, he and Marie Curie prepared radium in metallic form in visible amounts ...
Actinium-225 (225 Ac, Ac-225) is an isotope of actinium. It undergoes alpha decay to francium-221 with a half-life of 10 days, and is an intermediate decay product in the neptunium series (the decay chain starting at 237 Np). Except for minuscule quantities arising from this decay chain in nature, 225 Ac is entirely synthetic.
[5] [6] He was aware of the discovery of actinium by André-Louis Debierne. In publications from 1899 and 1900 Debierne does not give the exact procedures to obtain actinium, but from the description of chemical properties which he described as similar to titanium (1899) or similar to thorium (1900) it was clear for Giesel that the two elements ...
Actinium-225 is a member of the radioactive neptunium series; [60] it was first discovered in 1947 as a decay product of uranium-233 and it is an α-emitter with a half-life of 10 days. Actinium-225 is less available than actinium-228, but is more promising in radiotracer applications. [ 30 ]
Hahn pursued a report by Stefan Meyer and Egon Schweidler of a decay product of actinium with a half-life of about 11.8 days. Hahn determined that it was actinium X . He also discovered that at the moment when a radioactinium (thorium-227) atom emits an alpha particle, it does so with great force, and the actinium X experiences a recoil.
André-Louis Debierne had previously (in 1899 and 1900) reported the discovery of a new element actinium that was supposedly similar to titanium and thorium, which cannot have included much actual element 89. But by 1904, when Giesel and Debierne met, both had radiochemically pure element 89, and so Debierne has generally been given credit for ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 2 January 2025. Periodic table of the elements with eight or more periods Extended periodic table Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium ...