Water

• Diatomic elements


  Elements composed of two atoms
• Identifying if water is pure

  Check melting point or boiling point
• Water is not pure if


  Melting point and boiling point change
• Testing for presence of water


  Know equation
• Water is a universal solvent
• Sources of drinking water in Malta


  • Rock salt
  • Sea water
• Desalination of sea water

  1. Distillation

  2. Reverse osmosis
• Separation of components in rock salt


  1. Remove bacteria/micro-organisms by chlorination

  2. Remove insoluble substances by filtration

  3. Remove soluble salts by crystallization
• Separation techniques


  1. Filtration

  2. Evaporation to dryness/Crystallization

  3. Distillation
• Ionic bonding


  Bonding between a metal and a non-metal
• Properties of ionic substances


  • Explained by their structure
• Types of hard water


  • Temporary
  • Permanent
• How hard water forms

  1. Using Calcium/Magnesium hydrogencarbonate

  2. Know equations
• Removing temporary hardness


  Know equation
• Removing both temporary and permanent hardness

  Know equations
• Hard water


  • Does not lather easily with soap
  • Reacts with soap to form scum