190 Dr. Tycho E:son Auren on 



KalQu f° r a certain group is drawn so as to cut the X-axis, 

 the section thus cut off corresponding to the value Z = c will 

 give the number of electrons of the inner region in the 

 group mentioned. By means of a graphical construction we 

 accordingly find that the elements Cr (Z = 24)— Ni(Z= 28) 

 form a group having an inner region containing 18 electrons, 



Fig. 2. 



500 



400 



300 



200 



J00 



H 

 a. 



Cu 



Apt 

 Pet*. 



S H^ 



Be C o M 9 °'-' a 

 H U\B\n\ F"2 



24 



30 



40 



50 



and that the elements Cu (Z = 29) — Rh (Z = 45) form another 

 group whose inner region is characterized by 24 electrons. 

 It must be mentioned that for the last elements in the latter 

 of the just-mentioned groups there may be some uncertainty 

 for the above-given reasons, the more so as the values 



