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Actinium is a soft, silvery-white, [17] [18] radioactive, metallic element. Its estimated shear modulus is similar to that of lead. [19] 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. [20]
André-Louis Debierne (French pronunciation: [ɑ̃dʁe lwi dəbjɛʁn]; 14 July 1874 – 31 August 1949) was a French chemist.He is often considered the discoverer of the element actinium, though H. W. Kirby disputed this in 1971 and gave credit instead to German chemist Friedrich Oskar Giesel.
Perey announced the discovery of the never-before-seen element 87 as a note in the Comptes Rendus presented at the Académie des Sciences by Jean Baptiste Perrin on 9 January 1939 with the title "On an element 87, derived from actinium." [5] Perey's discovery was announced by Perrin, not Perey herself, because she was only a laboratory ...
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 research resulted in the successful identification of a new element in the decay chain between uranium-235 and actinium, later named protactinium. The discovery of protactinium completed the early version of the periodic table proposed by Dmitri Mendeleev, who predicted the existence of an element between thorium and uranium in 1871. [5]
The discovery of actinium by Debierne was however questioned in 1971 [27] and 2000, [28] arguing that Debierne's publications in 1904 contradicted his earlier work of 1899–1900. This view instead credits the 1902 work of Friedrich Oskar Giesel , who discovered a radioactive element named emanium that behaved similarly to lanthanum.
Otto Hahn (German: [ˈɔtoː ˈhaːn] ⓘ; 8 March 1879 – 28 July 1968) was a German chemist who was a pioneer in the field of radiochemistry.He is referred to as the father of nuclear chemistry and discoverer of nuclear fission, the science behind nuclear reactors and nuclear weapons.
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.