534 Sir J. J. Thomson on the Structure of 



for clearness, always in what follows represent 4, 5, ft, 7, 8 

 electron atoms by the symbols C, N, 0, F, Ne respectively, 

 while we shall represent the one-electron atom by H. Con- 

 sider the combinations in which the C, N, . . . atoms form 

 part of a molecule in which there are two cells together 

 containing 12 electrons. The possible combinations are given 

 in the following table : — 



Two cells — quadruple connexion. 



C.Ne, C.F.H, *COH 2 , *CNH 3 , *C 2 H 4 , *N 2 H 2 , 

 *NOH, NF, *0 2 . 



When there are 13 electrons in the two cells we have the 

 following results : — 



Two cell — triple connexion. 



C.Ne.H, C.F.H 2 , COH 3 , CNH 4 , C 2 H 5 , N.Ne, 

 N.F.H, NOH 2 , N 2 H 3 , OF, 2 H. 



When there are 14 electrons in the two cells we have the 

 following results : — 



Two cells — double connexion. 



CNeH 2 , *C.F.H 3 , *COH 4 , *CNH 5 , *C 2 H 6 , N.NeH, *NFH 2 , 

 *NOH 3 , *N 2 H 4 , OF.H, *0 2 H 2 , *F 2 , ONe. 



Of these only those marked with an asterisk fulfil the 

 conditions required for the ordinary theory of valency. The 

 theory does not assert that all these compounds can be formed: 

 for example, we have included compounds containing the 

 8-electron atoms, these are the atoms of the inert elements. 

 Owing to the very small attraction which such atoms exert on 

 other atoms, it is not at all likely that such compounds can be 

 prepared ; or, again, some of the compounds might break up 

 with great rapidity into still more stable forms. All that the 

 theory involves is that such molecules would be saturated 

 and would be stable if they were subject only to small 

 disturbances. 



It will be noticed that practically all the compounds where 

 the two cells have two electrons in common, i. e. are united 

 along an edge, fulfil the condition of being in accordance with 

 valency principles ; that for those where the cells have four 

 electrons in common a considerable number are in accordance: 

 while none of those which have three electrons in common 

 satisfy valency conditions. We can see without much difficulty 



