Grosse, Aristid

Produced in a pure form by Aristid Victor Grosse (1905-1985). 

Apparatus used by Dr. Aristid V. Grosse in his researches on protactinium. 

The probable existence of protactinium was predicted as early as 1871 by Mendeleev to fill up the space on his peiiodic table between thorium (at, no. 90) and uranium (at. no, 92). He termed the unconfirmed element ekatantalum. In 1926, O. Hahn predicted the properties of the element in considerable detail, including descriptions of its compounds. In 1930, Aristid v. Grosse isolated 2 milligrams of what then was termed ekatantalum pentoxide and showed that element 91 differed m all reactions with comparable amounts of tantalum compounds with exception of precipitation by NH3. However, credit for the discovery of protactinium generally is attributed to Lise Meitner and Otto Hahn in 1917,... 

Historically, the fluoride complexes are most important. Aristid Von Grosse (1934) used K2PaF7 in his determination of the atomic mass of Pa in 1931. Colourless crystals of this and other complexes MPaFe, M2PaFv, and MsPaFg (M = K, Rb, Cs) can be obtained by changing the stoichiometry, e.g. ... 

The demonstration vindicated Bohr s hypothesis, but it also led Briggs to even greater suspicion of the value of natural uranium it was very doubtful, he reported to Watson on April 9 whether a chain reaction can be established without separating 235 from the rest of the uranium. Nier, Dunning and their collaborators Eugene T. Booth and Aristide von Grosse had written much the same thing in the Physical Review on March 15 ... 

The seven remaining gaps in the periodic table were gradually filled, although not without further controversy in spite of the conclusive nature of Moseley s atomic number method. The first of these was element 91, discovered by Otto Hahn and Lise Meitner in 1917. The element behaved in the manner described by Mendeleev, who had given it the provisional name eka-tantalum. It now became known as protactinium but was not isolated until the year 1934 by Aristide Grosse in Germany. 

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