112 



METALS AND THEIR COMBINATIONS. 



Potassium, f 



Sodium, 



Barium, 



Calcium, 



Strontium, 



Magnesium, i 



Cadmium, 1817, by Stromeyer. 

 Lithium, 1817, by Arfvedson. 

 Aluminium, 1828, by Wohler. 



i H. Davy discovered methods for the separation 



of these metals from their oxides. 



Valence of metals. 



Univalent. 



Lithium, 

 Potassium, 

 Sodium, 

 Silver. 



Bivalent. 



Barium, 



Calcium, 



Strontium, 



Magnesium, 



Cadmium, 



Zinc, 



Copper, 



Mercury. 



Trivalent. 



Bismuth, 

 Gold. 



Bi- and trivalent. 



Aluminium, 



Chromium, 



Cobalt, 



Iron, 



Manganese, 



Nickel. 



Bi- and quadrivalent. 



Lead, 



Platinum, 



Tin. 



Tri- and quinquivalent. 

 Antimony, 



Arsenic. 



Sixvalent. 

 Molvbdenum. 



Occurrence in nature. 



a. In a free or combined state. 



' c ' I Almost exclusively in the metallic state. 



Platinum, J 



51 ver, ^ g meta ] s or su iphides. 

 Mercury, J 



Bismuth, generally metallic, also as oxide and sulphide. 

 Copper, rarely metallic ; chiefly as sulphide, oxide, and carbonate. 



