NO. II STRUCTURE OF THE ATOM PARSON 3 



emission, and the radioactivity : in the properties of the outer shell 

 there is a periodicity, in those of the core not. To this brief sketch 

 might be added the magnetic properties as obviously being due to the 

 behavior of the outer part of the atom. 



Now there is no theory that is able to explain, to any appreciable 

 extent, both sets of phenomena. Nor even is there any that shows 

 much promise in connection with the properties of the outer shell 

 alone — especially the chemical and magnetic properties of the atom : 

 most of the recent work (by Rutherford, Moseley, and others) has 

 emphasized the other part of the problem — the properties of the core, 

 or nucleus of the atom. Bohr's theory, based upon the conception 

 of the nuclear positive charge, gives an interesting treatment of the 

 problem of spectrum series, but its chemical application is very 

 meager indeed (see §8). On the other hand, the present theory, 

 since it originated in a study of the simpler aspects of chemical 

 affinity, emphasizes the properties of the outer shell, though not 

 necessarily at the expense of the other set of properties. 



The essential assumption of this theory is that the electron is itself 

 magnetic, having in addition to its negative charge the properties of 

 a current circuit whose radius (finally estimated to be 1.5 X io~ 9 cm. : 

 see §16) is less than that of the atom but of the same order of 

 magnitude. Hence it will usually be spoken of as the magneton. It 

 may be pictured by supposing that the unit negative charge is dis- 

 tributed continuously around a ring which rotates on its axis (with 

 a peripheral velocity of the order of that of light: §§5, 6) ; and 

 presumably the ring is exceedingly thin. It might at first sight be 

 supposed that if the electron were really thus magnetic, this property 

 would have been detected in the behavior of kathode rays, but it will 

 be shown later (§18) why it could not. 



This rotation of a ring-shaped negative charge is intended to 

 replace the usual conception of rotating rings of electrons in pro- 

 viding that orbital motion of electricity which is required by all 

 theories of the magnetic and optical properties of atoms. No 

 attempt will be made, however, to discuss the internal structure of 

 the magneton. 



With regard to the positive part of the atom, it will be necessary 

 to avoid Rutherford's conception of a nucleus of very small dimen- 

 sions — while fully recognizing the value of the evidence upon which 

 he bases it — because it could not allow magnetons to take up the 

 configurations that are essential to this theory, while the uniformly 

 charged sphere of the Kelvin or Thomson " atom " is particularly 



