Perey, Marguerite francium discovered

Francium (Fr, [Rn] . 1), name and symbol, after France, the country where it was prepared (Curie Institute in Paris). Discovered (1939) by Marguerite Perey. Very rare in nature, artificially prepared, highly radioactive. 

Marguerite Catherine Perey, an assistant to Marie Curie, is credited with the discovery of francium-223 in 1939. Perey discovered the sequence of radioactive decay of radium to actinium and then to several other unknown radioisotopes, one of which she identified as francium-223. Since half of her sample disappeared every 21 minutes, she did not have enough to continue her work, but a new element was discovered. 

The element francium is named for the country of France and its most stable isotope is known as actinium K. Dimitri Mendeleev assigned it the name eka-cesium prior to its actual discovery, although at this time it was also known as russium, virginium, and moldavium. Marguerite Perey, a one-time assistant of Marie Curie, discovered francium in 1939. It is not found in its elemental state and less than one ounce is thought to exist in Earth s crust at any one time. 

Francium may be the rarest element found on Earth s surface. Some experts believe that no more than 15 grams (less than an ounce) of the element exist in Earth s crust. The element was discovered in 1939 by French chemist Marguerite Perey (1909—1975). All isotopes of francium are radioactive. 

The element s name comes from the country France, and it was named in 1946 by Marguerite Perey (1909-1975), who discovered the element in 1939. Element 87 was predicted in 1871 by Mendeleev. He gave it the name eka-caesium. It was known first as actinium-K as a radioactive product of the decay of actinium, and it is the most unstable of the first 101 elements. Although francium occurs naturally, its short half-life means that there are only a few grams of the element at any time in the crust of the Earth. Because the longest lasting isotope of francium lasts only 22 minutes, it has no commercial uses. 

The last discovery of an alkali metal occurred almost 80 years later. In 1939, Parisian physicist Marguerite Perey (1909-75) observed an unusual rate of radioactive decay in a sample of a salt of actinium (element 89). She managed to isolate the new element, showed that it was an alkali metal, and named it francium in honor of her native country, France. Because francium s longest-lived isotope has a half-life of only 21 minutes, francium is the rarest element below element 98 in the periodic table, which explains why francium was discovered much later than the other radioactive elements in that part of the table. 

Marguerite Perey worked on the investigation of very pure actinium in France in 1939. She found a particles and could show that these did not come from protactinium. Moreover, she could follow an element growing in the actinium sample, an element with p activity. After dissolving the sample she found that the element with p activity did not follow barium in precipitation of barium carbonate. Nor did it follow lead in lead sulfide or cerium in cerium(iv) hydroxide precipitation. However, it was carried by cesium when cesium perchlorate was precipitated. Element number 87 ought to be an alkali metal, a new element that Margeruite Perey had discovered. She named it francium after her native country. 

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