Short Summary

Chapter 3, Metals and Non-metals, explores the physical and chemical properties of metallic and non-metallic elements, ionic bonding, metal extraction, and corrosion prevention. Metals are generally malleable, ductile, sonorous, and good conductors of heat and electricity, with silver and copper being among the best conductors, although there are notable exceptions such as liquid mercury, soft alkali metals like sodium and potassium, and low-melting metals such as gallium and caesium. Non-metals generally do not possess these properties, although exceptions include lustrous iodine and electrically conductive graphite. Metals generally react with oxygen to form basic oxides, while aluminium and zinc form amphoteric oxides that react with both acids and bases. Their reactions with water vary according to their reactivity, ranging from violent reactions with cold water in the case of sodium and potassium, to reactions with steam in the case of aluminium, iron, and zinc, while metals such as copper and gold do not react with water. Metals higher in the reactivity series can displace less reactive metals from their salt solutions. Ionic compounds are formed through the transfer of electrons from metals to non-metals and have high melting and boiling points because of strong inter-ionic forces; they conduct electricity in their molten or aqueous states. In the extraction of metals, ores are first converted into oxides through roasting, which involves strongly heating sulphide ores in excess air, or calcination, which involves heating carbonate ores in limited air. The resulting metal oxides are then reduced using carbon, thermite displacement reactions with aluminium, or electrolytic reduction for highly reactive metals such as sodium. Metals can undergo corrosion when exposed to air and moisture, producing substances such as black silver sulphide, green basic copper carbonate, or rust on iron. Corrosion can be prevented through methods such as galvanisation, which involves coating iron with zinc, anodising, and alloying, with examples of alloys including solder, brass, and amalgams.