[young] 



CALCULATION OF ATOMIC DIAMETERS 



53 



10 



20 



30 



40 50 60 



ATOMIC niUMBCR 



70 eo fo 



Fig. 1 



Nickel inclusive, from Rubidium to Palladium inclusive (excepting 

 Zirconium), from Barium to Platinum inclusive, and Thorium and 

 Uranium are the groups of the paramagnetic elements. Further, the 

 most strongly paramagnetic elements, such as the family of the Rare 

 Earths, and the ferromagnetic elements. Iron, Cobalt and Nickel, lie 

 in the very minima of the atomic volume curve. On the other hand, 

 the diamagnetic elements with the sole exception of Zirconium will 

 be found on the ascending slopes of the peaks of the curve. There is 

 thus a very sharp demarcation in the distribution of the magnetic 

 properties among the elements, the paramagnetic properties starting 

 off weakly in each period then increasing to a maximum and finally 

 the transition to diamagnetic elements in the latter part of each 

 period. There must be in this some repeated peculiarity of the 

 atomic structure of the elements. In a recent work by Bohr^ on the 

 relation of the atomic structure and the properties of the elements 

 there is a discussion of the magnetic properties of the elements, in 

 which Bohr expresses the opinion that "in the fourth and later periods 

 there is a break in the very symmetrical inner structure of the atom 

 which obtains in the earlier periods, and this lack of symmetry 



sBohr, Zeit. f. Physik, 9, p. 1, 1922. 



