the Hydrogen Molecule. 1037 



Two of the electrons of the molecule are contracted (or 

 flattened) say by the amount Ab { while the other two are 

 expanded by a slightly different amount, say A6 2 . Hence 

 the change in the internal energy of the whole molecule 

 from the state of free atoms may be written 



AE = 2(-0-236xl0 2 e)| 2 (A5 1 -A6 2 ). . . (41) 



The expansion of the minor axis Ab 2 may he assumed to 

 be greater than the contraction Ab 1} so that one must supply 

 energy to the molecule to restore it again into two separate 

 atoms. 



This is conceived to be the place where energy must be 

 supplied to separate the two hydrogen atoms of the molecule^ 

 and the energy on this view is not only interatomic but also 

 interelectronic. Using the experimental value of the energy 

 of dissociation per H molecule as 5"8xl0~ 12 erg as the 

 value of AE in (11), it appears that 



A^-A^sHxlO-Wcm (42) 



That is to say, the difference in the change of the minor 

 axes of the two electrons in the one atom is very small indeed 

 in order to correspond with what may be regarded as a 

 rather large energy change. This is because the total 

 energy content of the electron, mc 2 , is 8*08 X 10" 7 erg, and 

 far exceeds the order of magnitude of the energies concerned 

 in chemical transformations, of order 10 -12 erg. Since the 

 actual radms, b, of the electron is of an order a million 

 times larger than (42) it seems most probable that the 

 change in the shape of one electron (A b) is of an order 

 less than say the ten thousand part of the original radius. 



Any change in the shape of the electron involves a corre- 

 sponding change in its mass, but this change is so small that 

 the change in mass must escape experimental detection, and 

 this is true for the additional reason that the mass of the 

 electron is already an almost negligible part of the atom 

 itself. But this minute change is, however, entirely suffi- 

 cient to manifest itself through the energy liberated or 

 absorbed. 



The small change in shape of the electron caused by the 

 forces above mentioned when the atoms unite into one 

 molecule, and which act in the proper sense to effect such a 

 change, may account entirely for the observed energy of 

 dissociation in all chemical combinations. This example 

 using hydrogen as an illustration points to the seat of all 



