Oxides

• Oxides of metals are bases (they will react with acids to form salts)
• Oxides of non-metals are acids (they will react with acids and bases)
• Some metal oxides are amphoteric (they will react with acids and bases)
• Some non-metal oxides are neutral
• Oxide ions immediately react with water and then dissolve to form hydroxide ions. Although potassium hydroxide solution exists, potassium oxide solution does not exist

Metal Oxides – compounds of metal cations and the oxide anion O2-. Few metal oxides react or dissolve in water. The main metal oxides which are considered soluble are potassium and sodium oxides, as well as barium, calcium, and magnesium oxides in decreasing amounts. Metal oxides are either basic or amphoteric. The basic oxides will only react with acids, while the amphoteric oxides will react with both acids and bases.

Non-metal Oxides – covalently bonded compounds of a non-metal with oxygen. They are either acidic or neutral oxides. The acidic oxides react with water immediately and dissociate to form acid solutions while the neutral oxides do nothing when placed in water. The acidic oxides will react only with bases, while the neutral oxides are unreactive with both acids and bases.