155 



XIII. A Table of the Radioactive Elements which indicates: 

 their Structure. By Ingo W. D. Hackh, Professor of 

 Chemistry, College of Physicians and Surgeons of San 

 Francisco, Cal., U.S.A.* 



IN a recent paper on the " Conception of a Chemical 

 Element as enlarged by the study o£ radioactive 

 change/' Prof. F. Soddyf has given a masterly summary 

 of the present status of our knowledge concerning the radio- 

 active elements. From a study of the phenomena of disin- 

 tegration in connexion with the new periodic table J, it 

 becomes possible to ascribe a partial atom-structural formula 

 to each of the radioactive elements §. Thus it has been 

 shown that the emission of a helium particle (alpha-radiation) 

 is accompanied by the shift of two " metastasic " electrons 

 from the outer or valency ring into the next inner and 

 unstable ring, while the emission of an electron (beta- 

 radiation) is accompanied by the shift of one " metastasic " 

 electron from the next inner and unstable ring to the outer 

 or valency ring. In the calculation of the partial atom- 

 structural formulae the changes between the first and last 

 member of each series have been utilised, for this difference 

 furnishes a tangible basis of the structural composition of 

 the respective atom. 



Assuming that each transformation is caused by the 

 emission of one helium particle resp. one electron from one 

 atom, the atom-structural formula for uranium 1 is w.He 8 E 8+6 

 and for thorium t . He 6 E 8+4 , while the last members of each 

 series have a structure formula of u . E 4+4 for lead from 

 uranium and t .E 4+4 for lead from thorium. The difference 

 in the structure formulae of the first and last members is 

 therefore in the uranium series 8 He and 6E, indicating 

 eight alpha- and six beta-changes, while in the thorium series 

 the difference is 6 He and 4E, indicating six alpha- and four 

 beta-changes. 



The relationship among the members of the uranium- 

 radium, uranium-actinium, and thorium series is shown in 



* Communicated by the Author. 

 t Journ. Chem. Soc. cxv. p. 1 (1919). 



% Joum. Am. Chem. Soc. xi. p. 1023 (1918) ; Am. Journ. Science, 

 xlvi. p. 481 (1918) : Astrophys. Journ. xlviii. p. 241 Q918). 

 § Phys. Eev. xiii. p. 165 (1919). 



