■orce 



zes between Atoms and Chemical Affinity. 



771 



energy necessary for the transference of a corpuscle from 

 one atom to the other : in other words, A and B must be 

 well separated in the electrochemical series. If the sepa- 

 ration is great, the transference of the electricity may take 

 place without the help of other molecules ; but if the intra- 

 molecular ionization has to be brought about by the help of 

 such molecules, then 



(2) There must be a strong field of electric force round 

 AB, so as to attract the molecules M 1; M 2 . It is not 

 necessary that molecules should attach themselves to both 

 the atoms in AB, although the ionization will occur all the 

 more readily if they do. 



(3) The molecules M x , M 2 must be strongly attracted by 

 the field exerted by AB ; thus, if they produce electrical 

 effects analogous to those produced by electric doublets, the 

 moments of these doublets must be large. 



We see from this that intra-molecular ionization will only 

 occur in a certain type of molecule, and only molecules 

 with certain properties will be able to produce it. 



Chemical Ejects produced by the Electric Fields arising 

 from Intra-molecular Ionization. 



We have seen that the moment of the electrical doublets 

 in the molecules of some gases in which intra-molecular 

 ionization takes place, are so large that the work required to 

 separate two such doublets is quite comparable with that 

 required in some cases to separate the atoms in a molecule. 

 It would seem from this that we might expect that two 

 molecules might, under suitable conditions, be held together 

 by the attraction between two such doublets. 



Let us consider the case of a diatomic molecule AB held 

 together, either by the forces exerted by the intra-atomic 

 doublets in A and B respectively, or by these in addition to 

 the forces between the charges on A and B when intra- 

 molecular ionization has taken place ; we need not for the 

 moment distinguish between these cases. Outside the 

 molecule there will be a stray electric field, whose magnitude 

 will depend largely upon the nature of the atoms A and B. 

 The stray field will not be so intense as that between the 

 atoms, and so might be unable to bind another atom in 

 which there are only intra-atomic doublets which arc 

 necessarily of small moment, as there is no room inside 

 the atom for a wide separation of the poles of the doublet. 

 Again, any compound with an atom would be " unsaturated " ; 

 thus the kind of combination we are considering will be 

 between molecules, and not between atoms. 



