490 HISTORICAL INTRODUCTION TO CHEMISTRY CHAP. 



shown in the following table (Moseley, Phil Mag., Dec v 

 1913, 26, 1028) : 



In this table Q = j -y - [ , where v is the frequency of the 

 I v ) 



line of longer wave-length and v is a constant derived from 

 the study of ordinary series spectra. It will be seen that Q 

 gives a series of integral numbers one unit less than the 

 atomic numbers reckoned from H i, He 2, Li 3, etc., that it 

 leaves an integer vacant for scandium, and finally that the 

 Q-numbers show precisely that exact relationship which Prout 

 postulated incorrectly in the case of the atomic weights. It 

 is further of interest to notice that the value of Q is one 

 unit greater for nickel than for cobalt, although nickel has 

 the smaller atomic weight, thus justifying Mendeleeff's 

 arrangement of the transition-elements in the order Cr, Mn, 

 Fe, Co, Ni, Cu, Zn. 



This " K series " of spectra is continued up to Ag(47) = 

 107-88. But already at Zr(4o) = 90'6, an "L series" of 

 spectra begins ; this is more complex, containing some five 

 chief lines, but the same laws apply to these lines as to the two 

 lines of the K series, and the atomic numbers can thus be 

 carried forward as far as Au(79)= 197*2. 



A complete list of atomic numbers and atomic weights is 

 shown in Table F, p. 491. The atomic numbers deter- 

 mined experimentally by Moseley in 1913 and 1914 are 



