124 CHEMICAL PROPERTIES AND COMPOSITION 



difficulty, a fact that may be due to the large electric charge 

 associated with these, it is just these multivalent elements, 

 perhaps for that reason, in which the negative character is 

 most persistent. A comparison of chlorine, oxygen, and 

 nitrogen will show this best. 



According to p. 84, the negative character of chlorine is 

 the most marked, that of oxygen less, of nitrogen least. 

 But if their respective influences on compounds into which 

 they enter be compared the order will be found reversed, 

 nitrogen giving the group a more decided negative character 

 than oxygen, and chlorine less than the latter. 



This may be shown qualitatively by the fact that 

 chlorine does not make carbon capable of combining with 

 metals, chloroform, CHC1 3 , being perfectly neutral, whilst 

 nitrogen in hydrocyanic acid, NCH, has produced a distinctly 

 acid character ; oxygen does the same, but to a much less 

 extent, in compounds of the type 



XCOCH 2 COX, 



as in malonic ethyl ester (p. i so). Later some other cases 

 of the kind will be mentioned. 



B. Change in Velocity of Reaction under the Influence 

 of certain Elements and Groups. 



Besides the actions brought together above under a single 

 point of view, due to the tendency to ionization which 

 certain elements carry with them into compounds, there 

 are others to be considered, which appear with striking 

 regularity. The former appeared chiefly as displacing 

 equilibrium, since they increase or decrease acidity, and so 

 affect the dissociation constant. The phenomena we have 

 now to consider result in an increase in velocity of reaction, 

 or, as it may be called, in a loosening of the compound. 

 Partly, this action too may be referred to a tendency to 

 ionization, and it will appear in the following, e. g. that 

 introduction of negative groups regularly tends towards 

 breaking up a carbon structure, and that here too the action 



