66 THE TRUE VALUE OF a OF VAN DER WAALS' 



There is, however, another consideration which may throw some 

 light on the cause of the possibly exceptional position of these sub- 

 stances, and why they have in their molecules fewer valences than 

 we expected to find there. These valences are probably nothing- 

 else than the valence electrons. This to be sure introduces a some- 

 what different idea of valence than that with which I started. At 

 first I believed, or assumed, that the chemical attractions between 

 the atoms were electrostatic in nature. The valences thus became 

 both positive and negative. Accordingly I supposed that the number 

 of negative valence electrons in the molecule would be only one 

 half the number of total valences found by this method. It has, 

 however, since been suggested bv Ramsay and G. N. Lewis, and 

 I believe still earlier by Sutherland, that the atomic attractions were 

 electromagnetic and not electrostatic. If this is the case then the valence 

 numbers we have found, or which we are using in our computa- 

 tions, are in reality only the negative valence electrons. When we 

 find 16 valences in a molecule, it means that there arc 16 valence 

 electrons in that molecule. This view, it seems to me, has a great 

 deal in «its favor and wc may provisionally adopt it. At any rate 

 it helps us very much in understanding the exceptional position of 

 these few compounds. Perhaps those compounds which are called 

 „polar" have in them atoms which have lost some of their negative 

 electrons. C0 2 and S0 2 at least would be such compounds and to 

 a less degree perhaps CO might also be called polar. Now it is the 

 essence of an 'oxidation, according to the modern view, that there 

 is an exchange of electrons, the substance or atom oxidized losing- 

 one or more electrons and the substance oxidizing acquiring them. 

 If we examine the exceptions from this point of view they are of 

 great interest. Wc find that the oxidizing substance, 2 , has in its 

 molecule only two negative electrons, whereas each atom should 

 have two and the molecule is, therefore, entitled to four. It is two 

 negative electrons short, and it would be for this very reason that 

 it has oxidizing powers. In CO and C0 2 the carbon has been 

 oxidized. That means that the carbon atom has lost some of its 

 usual negative valence electrons. It usually has four such electrons, 

 but in the act of oxidation it has lost some of them and the oxygen 

 has gained them. Thus in CO the carbon atom has been completely 

 stripped of its valence electrons and there are only two in the 

 molecule, namely those attached to the oxygen. Or at any rate 

 there are but two such electrons left. Possibly the oxygen and 

 carbon share them between them. Of course we cannot say just 

 where they are in the molecule. It it possible that the carbon has 



