Table 600 

 ATOMIC STRUCTURE 



(Harkins, Science, 70, 433, 463, 1929.) 



487 



If weight of proton (/>) + electron (c) = 1, atomic wt. = no. of protons + electrons in 

 atom, (pc) w = composition of complete atom, atomic weight (iv) . P, no. of protons in 

 atom, = IV. N = total number electrons in nucleus ; P — N = Z=i atomic number. 

 2N — P = isotopic number ; electronic number = no. electrons. 



The structure of the loosely bound nonnuclear electrons decides various chemical and 

 physical properties. The tightly bound nuclear atoms should produce periodic properties. 

 Abundance of atomic species reveals nuclear stability (possibility of other factors). High 

 stability shown by abundance of even electronic numbers. Species of odd electronic number 

 are so rare that only four have been discovered. There is high stability for isotopic num- 

 bers divisible by 4, a secondary stability when by 2. When N and P even, Z odd, earth's 

 crust 87.470 ; meteorites, 95.4 ; when N even, P, Z odd, 10.8, 2.1 ; Z even, P, N odd, 1.8, 2.5 ■ 

 P even, N, Z odd, 0.0007, 0.0. Lower left-hand rectangle of lower figure constitutes 99.9% 

 of all known material. 



Periodic System of 

 the Atomic Species 



1 ^ij«!ouzoLzz!:<io)Q.oio<^oiiii->usrii.uzuNoO<t«)iDi£(i:v)vN(ji:Eieaii.<iOi(/i<ni — xOOJunz 



Atomic Number Feb., 1930 



© Pure species even atomic number 



» •• odd 



• Mean iralue even ,, „ 



■ ,. ,. odd 



50 60 



70 



«o 90 



Smithsonian Tables 



