100 



In tlie polar bond tlie atoms aie ilioiiglit separated, in the non- 

 polar bond tliey penetiate into eacli other at definite places. 



There is still a third Uind of liond, whicli comes near to the 



Fig. la. 

 Lithium fluoride. 



Fig. 1Ö. 

 Water. 



non-polar bond, and is distinguished from it only in form, not in 

 natnie. 



It is seen from the symbol for water that the oxygen atom lias 

 still two pair of electrons in Ihe onler shell. These endow this 

 molecnle with the power to combine with other molecnies, and 

 especially with those of which one of the atoms lacks a few elec- 

 trons in the onter shell. 



■ Thus we must imagine that metal atoms which have ceded their 

 electrons to acid rests on the salt formation, can get saturated with 

 water molecnies, and Ihns form hydraled metal ions. This kind of 

 non-polar bond is that which was sui>pused to come abont through 

 by-valencies, and which is explained from the tendency to collect 

 eight (or sometimes more) electrons in the onter shell. 



It is easy to see that ammonia, though a saturated compound, can 

 combine with a great number of substances owing to the free 

 electrons in the outer shell. All these bonds are of quite the same 

 nature as those that come about through the principal valencies. 

 The penetration of these ammonia molecules into the metal atom 

 often gives it a more pronounced electro-|)ositive character. 



That this bond is really restricted to a 

 definite place of Ihe molecule, follows from 

 Meisenhiïimkr's investigation '), in which he 

 has succeeded in splitting up methyl ethyl 

 aniline oxide into its optical antipodes. The 

 four non-polar bonds, among which that where 

 the nitrogen with its free electrons, has 

 penetrated into the outer shell of the oxygen 

 find a place in the angles of a tetrahedron. 



Fig. 2. 

 Ammonia. 



1) Berichte 41, 3967 (19Ü8). 



