Chapter XV. 

 The Properties of Metallic Substances. 



1. The Metallic State. With the exception of the elements of the 

 argon group and the strongly electronegative elements of lower atomic 

 weight, elementary substances are metallic. Compounds between 

 strongly electronegative and strongly electropositive elements, as well 

 as compounds between the more electronegative elements, are non- 

 metallic; while compounds between distinctly metallic elements are 

 throughout metallic. Compounds between the less strongly electronega- 

 tive elements and the less strongly electropositive elements are often 

 metallic in the solid state. Thus the compounds of the alkali metals 

 and the metals of the alkaline earths with the elements of the halogen 

 and of the oxygen groups are non-metallic; while compounds of the less 

 electropositive elements, such as lead and iron, with the elements of the 

 oxygen group are often metallic. Within this class are also included 

 certain free electropositive groups, containing both metallic and non- 

 metallic elements, and possibly groups containing only nonmetallic 

 elements. Thus, the free group CH 3 Hg is metallic, 1 while certain of 

 the substituted ammonium groups form stable metallic amalgams. 12 

 There is also evidence that the quaternary substituted ammonium groups 

 are soluble in ammonia in the free state, and that in solution their prop- 

 erties resemble those of the alkali metals. 3 The property of metallicity, 

 therefore, is not to be looked upon as an atomic property, since various 

 groups of nonmetallic elements in the free state exhibit metallic 

 properties. 



The metals thus comprise a major portion of the elementary sub- 

 stances and a large number of compounds between metallic and non- 

 metallic elements. While nonmetallic compounds may, in a large 

 measure, be accounted for through the interaction of the negative elec- 

 trons with atoms, a similar theory of the constitution of metallic com- 

 pounds has not thus far been developed. One of the remarkable facts 



Kraus, J. Am. Chem. Soc. 35, 1732 (1913). 



McCoy and Moore, J. Am. Chem. Soc. 33, 273 (1911). 



Palmaer, Ztschr. f. Elelctroch. 8, 729 (1902) ; Kraus, loc. cit. 



384 



