the Molecule and Chemical Combination. 



529 



number which can be in equilibrium on the surface of a 

 single cell. A way in which these might be distributed with 

 4 electrons between the two atoms is shown in fig. 8, where 

 there is a double bond between the atoms A, B. 



Fisr. 8. 



When we proceed to consider the union of two five-electron 

 atoms, new considerations come in, for in the diatomic 

 molecule we have ten electrons, two more than can be accom- 

 modated on a single layer. A simple distribution of these 



where we have an outer cell, 



10 electrons is shown in fio-. 



Fig. 9. 



«j a 2 « 4 « 5 /5i j3 2 ft ft of 8 electrons, inside this are the two 

 positive charges and midway between these two electrons 

 « 3 ft which together with the double bond a x ft ft a. 2 help 

 to hold the positive parts together. With two atoms each 

 containing 6 electrons, there are 12 electrons to accom- 

 modate in a diatomic molecule. These will be sufficient to 

 surround each positive charge with a cell containing 8 elec- 

 trons, provided the cells have 4 electrons in common ; these 

 electrons coming between the two positive charges will form 

 a double bond tending to bind them together. 



When each of the atoms contains 7 electrons, we have 

 14 electrons at our disposal in the diatomic molecule ; these 

 are sufficient to surround each of the atoms with a cell of 

 8 electrons, provided the cells have' two electrons in common, 

 these two electrons forming a single bond. We might expect 

 as the two cells have only two electrons in common, while 

 those for the six-electron atom had four, that the cells 



