4:90 Hackh — Modification of the Periodic Table. 



A classification of the elements into nonmetals and 

 metals is easily made by considering the elements to the 

 left of the rare gases as nonmetals , those to the right as 

 light metals, and those in the lower half of the table as 

 the heavy metals. The carbon group furnishes the tran- 

 sition elements framing in the elements of the table and 

 guiding from one line to the other. 



Among other general properties common to elements in 

 certain areas of the table may be mentioned : 



The elements in the upper half of the table have the 

 highest electro-potential, the simplest spectra, colorless 

 ions and mostly soluble compounds, and possess mostly a 

 single valence. 



The elements in the lower half of the table have a 

 lower electro-potential, complex spectra, colored ions and 

 form complex double salts, and possess mostly more than 

 one A^alence. 



On the left side of the table are the electro-negative 

 elements forming acids. 



On the right side of the table are the electro-positive 

 elements, forming bases and oxysalts, sulphides, etc. 



In the center of the lower half are the amphoteric ele- 

 ments, forming weak acids, weak bases, many compli- 

 cated compounds and double salts, many insoluble and 

 colored ions. 



A new and striking feature of the table is also the 

 illustration of the somewhat notorious chemical affinity. 

 This often criticized term affinity is employed to express 

 the tendency or selective preference for certain elements. 

 Such a tendency exists and is characteristic of certain 

 regions in the table. We have for instance : 



Elements combining with nitrogen and forming typical 

 nitrides are those around boron : 



Ti 





Ca 



Sc 





Mg 



Al 



Li 



Be 



B 



Elements having a weak tendency to combine with 

 oxygen (the noble metals) are those neighboring gold: 



Ag 



Platin-metals Au Hg 



