16 



THE ROYAL SOCIETY OF CANADA 



Lead 



(207-1) 



(13). All of these results are in harmony with the wonderful 

 advances in radio-chemistry due to Soddy, Fajans, Von Hevesy and 

 others. It has been found that when a radiant emits an alpha particle 

 or helium nucleus, the chemical properties of the newly formed 

 radiant differ from the old. A fresh element is formed, a different 

 valency results, and the new radiant, relative to the old, is two columns 

 to the left in the periodic table. The atomic number has decreased 

 2, and the atomic weight about 4. But when a radiant ejects a beta 

 particle or electron, again there is a new radiant with different valency 

 and chemical properties, but there is a move of one column to the 

 right in the periodic table, a gain of one in the atomic number and no 

 change in the atomic weight. 



A brief example of the whole scheme applicable to all radiants 

 is given below. — 



Column 



IV. 



V. 



VI. 



At. wts. 



In the case of these radiants Ur 1 evicts an a particle and gives 

 rise to Ur X 1. The latter and Ur X 2 respectively emit a ft particle. 



It should be added that the short lived product Ur X 2, or 

 "brevium," was discovered by this theory after it had been formulated 

 from the known behaviour of other radiants. 



It will be seen that Uranium 1 and 2 are in the same column 

 and have the same atomic number, but that their atomic weights 

 differ by 4. Such substances have chemical properties so identical 

 that they are called ''inseparables,'" or "non-separables," or "isotopes, 1 



