Chemical changes

• Displacement reaction


  Occurs when a more reactive metal displaces a less reactive metal from a compound
• Reactivity of metals


  • Most metals react with acids to make salts and hydrogen
  • Metal carbonate also reacts with acids to make salt, carbon dioxide and water
• Group 1 metals


  • More reactive than hydrogen
  • Produce hydrogen gas when reacting with acids
• Displacement reactions


  Used to obtain metals from their ores, by displacing with a more reactive metal
• Oxidation


  Loss of electrons
• Reduction


  Gain of electrons
• Neutralisation


  Acid reacts with alkali to produce salt and water
• pH scale


  • Acid has pH < 7
  • Alkali has pH > 7
  • Water is neutral and has pH = 7