ELECTRONS 89 



planetary electron too many for a really satisfactory 

 configuration such as is represented by the planetary 

 electrons in the neon atom. Chlorine on the other hand 

 lacks one electron of the eighteen which would assume 

 the stable arrangement of the argon atom. 



A sodium atom is like a human being wrought upon 

 by two conflicting emotions. If it should lose a planet- 

 ary electron its remaining satellites would have a satis- 

 fied configuration, but the urge for an equal number of 

 protons and electrons would then be effective and the 

 atom would merely have changed the kind of its dis- 

 content. On the other hand, the chlorine atom would 

 be better off with an additional electron in its planetary 

 spheres, if it were not that, for it also, the urge of equal- 

 ity and electrical neutrality would then be dominant. 

 One has an electron to lose : the other, one to gain. They 

 meet apparently on the same plane of mutual profit 

 as do buyer and seller in the ideal case of business trans- 

 actions. An electron is transferred. But neither 

 buyer nor seller dares balance his books thereafter. 

 The only solution is to remain together so that for pur- 

 poses of accountancy the transaction may be considered 

 incomplete and yet both may have the satisfaction 

 which is the profit. This seems to be the basis of the 

 existence in combination of a sodium and a chlorine 

 atom as a molecule of sodium chloride, the common salt 

 of the table. In fact, in a crystal of salt the various 

 atoms are arranged in orderly rows in such a manner as 

 to make the accountancy surprisingly satisfactory to 

 each atom. Above and below, in front and behind,' to 

 right and left of each sodium atom there is one of 



