Actinium chloride

Radium. Ra at. wt 226 (mass number of most stable isotope) at. no. 88 valence 2. A radioactive alkaline earth meta], Occurrence in earth s crust approx ]0-d% by wt. Natural isotopes 223, actinium X 224, thorium X 226 228, mesothorium 1. 22 Ra is a product of disintegration of uranium and is present in al] ores contg uranium. Separated in the form of a salt by P. and M. S. Curie from the pitchblende nf Joachimsthal, Bohemia Curie et at.. Compt. Rend. 127, 12]5 (1898). [soln of the element by electrolysis of an aq soln of radium chloride Curie, Debierne. ibid. 151, 523 (1910). 12 Ra iT, 6.7 years) produced by disintegration of thorium (I12Th) discovered in 1907 by O. Hahn in monazite residues from isolating thorium. Zaire (Congo) is the main producer of radium, Canada next. Clinical evaluation in... 

Freeman and Smith (32) have prepared the anhydrous chlorides of a number of lanthanides and of thorium by dehydrating the hydrated chlorides with thionyl chloride. Although efforts to obtain anhydrous plutonium trichloride in this way were unsuccessful, it is believed that this may be a useful procedure for actinide elements such as actinium, americium, and curium that have a particularly stable (III) oxidation stage. In general, aqueous methods for preparing tetrachlorides are of little value but anhydrous trichlorides, particularly of the transuranium elements, can be obtained readily from the hydrated trichlorides by dehydration in an atmosphere of hydrogen chloride. 

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