Marguerite Catherine Perey – discoverer of francium element

Marguerite Catherine Perey – discoverer of francium element

Marguerite Catherine Perey

Biography & Contributions

Marguerite Catherine Perey was a French physicist born on October 19, 1909 – died on May 13, 1975. Perey was discovered francium element by purifying samples of lanthanum that contained actinium.

Perey spent a decade to extract actinium from all the other components of uranium ore, which Curie then used in her study of the decay of the element. A few years later Perey first noticed that the actinium she purified was emitting unexpected radiation. After further study she was able to isolate new element which she named francium.

Eka-caesium was discovered in 1939 by Marguerite Perey of the Curie Institute in Paris, France when she purified a sample of actinium-227 which had been reported to have decay energy of 220 keV. Perey noticed decay particles with an energy level below 80 keV. Perey thought this decay activity might have been caused by a previously unidentified decay product, one which was separated during purification, but emerged again out of the pure actinium-227.

Various tests eliminated the possibility of the unknown element being thorium, radium, lead, bismuth, or thallium. The new product exhibited chemical properties of an alkali metal, which led Perey to believe that it was element 87, caused by the alpha decay of actinium-227.Perey then attempted to determine the proportion of beta decay to alpha decay in actinium-227. Her first test put the alpha branching at 0.6%, a figure which she later revised to 1%.

Perey named the new isotope actinium-K (now referred to as francium-223) and in 1946, she proposed the name catium for her newly discovered element, as she believed it to be the most electropositive cation of the elements. Later it was named as francium.

Francium Element

Francium [Eka-caesium] is one of the two least electronegative elements, the other being caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon. Francium is the most unstable of the naturally occurring elements: its most stable isotope, francium-223, has a half-life of only 22 minutes. Francium coprecipitates with several caesium salts, such as caesium perchlorate, which results in small amounts of francium perchlorate.

It will additionally coprecipitate with many other caesium salts, including the iodate, the picrate, the tartrate, the chloroplatinate, and the silicotungstate. Francium also coprecipitates with silicotungstic acid, and with perchloric acid, without another alkali metal as a carrier, which provides other methods of separation.

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