CHAPTER III 



ACIDS BASES SALTS ANHYDRIDES DISSOCIATION- 

 NOMENCLATURE 



21. Groups of Elements. The chemical elements may 

 be roughly divided into three large groups: 



(1) Metals. These are base-forming elements. There 

 are somewhat more than a dozen of these elements that 

 are important. 



(2) Non-metals. These are acid-formers. The common 

 acid-forming elements are oxygen, sulphur, nitrogen, carbon, 

 silicon, boron, phosphorus, fluorine, chlorine, bromine, and 

 iodine. 



(3) Metalloids. Between the two groups (1) and (2) 

 are a few intermediate elements which act either as acidic 

 or basic, according as they are influenced by combination, 

 on the one hand with strong basic elements, or on the 

 other hand with strong acidic elements. These border-line 

 elements thus are seen to be rather indifferent in their 

 chemical affinities. The common metalloids are chromium, 

 aluminium, manganese, arsenic, antimony, and tin. 



22. Classes of Compounds. Most of the compounds of 

 inorganic chemistry are included in one of the four classes 

 acids, bases, salts, and anhydrides. The properties and 

 the composition of each of these classes must be studied 

 carefully in order to gain a working knowledge of chemistry. 



23. Acids. The most important acids are sulphuric, 

 [2804; hydrochloric, HC1; nitric, HNOs; phosphoric, 

 HaPOi; and acetic, HC2Hs02. If these or the score of 

 other commonly-occurring acids should be examined, they 

 all will be found to have the following characteristic prop- 

 erties: 



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