NO. II STRUCTURE OF THE ATOM PARSON 13 



predominating feature of the Periodic Scheme. On the other hand, 

 the magneton gives more or less independent units of valence, while 

 the explanation to which it leads for the " Law of Octaves " is 

 dependent ultimately upon the three-dimensional nature of space, 

 and the fact that of the simple figures which are symmetrical in three 

 dimensions the cube is alone in furnishing an arrangement of mag- 

 netons with a very low magnetic energy. 



§4. The Scope of Electrostatic Theories of Valence 



Since we have concluded that the atom cannot contain spherical 

 or " point " electrons in rotating rings, let us next consider what are 

 the possibilities of such electrons if they are supposed to be in a 

 state of rest in the atom. It must be borne in mind that anything 

 which is true for such electrons must also be a factor in the electro- 

 static part of the behavior of the magneton. 



The fundamental problem from a chemical point of view is to 

 show how two electrically neutral systems, such as atoms must be, 

 can attract one another at all; and an analogy originally due to 

 Lord Kelvin is typical of the way in which this question can be 

 approached on the basis of the electrostatic action of movable 

 charges. If a single electron 

 is situated within a sphere of 

 uniform positive electrifica- 

 tion of equivalent amount, the 

 whole is electrically neutral, 

 but the force required to drag 

 the electron out of its positive 

 sphere is the greater the more 

 dense the latter is, being in- 

 versely proportional to the 



square of its radius. If two such systems are brought into contact, 

 the smaller and denser sphere will just be able to extract the electron 

 from the other if the ratio of their radii is .695: 1.000, as in the 

 figure: now, if the two spheres are pulled apart, there will be an 

 electrostatic attraction between them, and they will resemble the ions 

 of a diatomic molecule like HC1. This principle holds true for all 

 kinds of electrons, and will have to be taken into account in subse- 

 quent developments of the present theory wherever necessary (see 

 §16), but its inadequacy as the sole basis of an explanation of chemi- 

 cal action is shown by the mere fact that it requires a higher atomic 

 volume for Hydrogen than for any halogen element. 



