The Groundtvork of the Viiiveise, Sec. 



63 



Element 



Atomic 

 ^Veight 



Average 

 Life 



Rays 



Emitted 



Ionium 



230 



2x10'^ years 



a 



Radium 



226 



2,440 years 



(A 



Niton 



222 



94 hours 



a 



Radium-A 



218 



4-3 minutes 



a 



Radium-B 



214 



38-5 minutes 



a 



Radium-C 



314 



28-1 minutes 



(I. and /3 



At this point a branching occurs in the series. Radiuni-C disintegrates 

 by two different processes, yielding respectively Radium-C^ and 

 Radium-Cs. Each of tliese then disintegrates as shown below. 



Radium-C^ 



214 



lO"** seconds 



a 



Radium-D 



210 



24 years 



(^ 



Radium-E 



210 



7-20 days 



iS 



Radium-F 



210 



196 days 



a 



End-product 



206 



Stable 



No rays 



Radium-C^ 



210 



1-9 minutes 



^ 



End-product 



210 



Stable 



No rays 



III— The 



Uranium 



-Actinium Series. 









Average 



Rays 



Element 





Life 



Emitted 



Uranium- Y 





2-2 days 



/3 



Uranium-Z (Eka-tantalum) 



? 



a 



Actinium 





5,000 years 



(i 



Radioactinium 





28-1 days 



a 



Actinium-X 





16-4 days 



a 



Actinium emanati( 



3n 



5-6 seconds 



a 



Actinium-A 





0-003 seconds 



a 



Actinium-B 





52-1 minutes 



(i 



Actinium-C 





3-1 minutes 



a 



Actinium-D 





6-83 minutes 



/>• 



End-product 





Stable 



No rays 



Note. — Uranium-Y is believed to be derived frqm Uranium-1, but tlie 

 exact connection has not yet been traced. The atomic weights 

 in the actinium series have not been detern)ined up to the 

 present. 



