chemical/physical change science

• Physical change


  A material may change its shape and size but no new substances are formed
• Chemical change


  New substances with different properties are formed
• Physical changes

  • The molecules of the substances remain the same before and after the change
  • Most are temporary and reversible
• Physical changes


  • Tearing paper
  • Changing the size of a pencil and eraser with use
  • Freezing water
  • Heating substances like water and iron
  • Melting of substances
  • Crushing a can
• Chemical changes


  • The molecules of the substances undergo changes to form molecules of new substances
  • Most are permanent and irreversible
• Changes in burning a candle

  1. Melting of wax (physical, reversible)

  2. Burning of cotton wick/candle (chemical, irreversible)
• Melting of butter and curdling of milk

  1. Melting of butter (physical, reversible)

  2. Curdling of milk (chemical, irreversible)
• Chocolate melting is an example of a physical change
• Physical changes


  • Freezing orange juice
• Chemical changes


  • Boiling an egg
  • Burning wood
  • Cooking sausage
• Types of changes


  • Reversible
  • Irreversible
  • Chemical
  • Physical
• Acid reaction in stomach


  Digests food