48 



The Structure of Protoplasm 



larly for the three of nitrogen and its single negative residual; and 

 also the two bonds of oxygen with its two negative residuals. When 

 a double bond occurs between atoms, this bond (19) makes an angle 

 of approximately 125° with the other single bonds present. It must 

 not be overlooked, however, that rotation on primary valence bonds 



Fig. 1. A. Diagram to show tetrahedral distribution of the two hydrogen 

 nuclei and two negative residuals in a water molecule. The distance between 

 the oxygen and hydrogen nucleus is approximately 0.96 A, and the two hydro- 

 gen nuclei make an angle of about 105° with the oxygen nucleus (15). B. Dia- 

 gram showing coordination of several water molecules around a central one 

 resulting from the attraction of the negative residual of one molecule for the 

 hydrogen nucleus, or proton, of another (15). 



may occur (19) so the shapes indicated may vary somewhat from the 

 model photographs shown. 



The radii of the various atoms are included in Table 3. An 

 additive law is effective for these; thus when two atoms, such as 



TABLE 3 

 Atomic Radii (19) 



