Page 2 - Lesson Notes
P. 2

  There is no change in the internal structure of the given substance.

               They are usually temporary and can be reversed.
               A temporary change in colour may take place.

               Very little energy (heat) is absorbed or released.

         Remember,  the  appearance  of  matter  changes  in  a  physical  change,  but  its  chemical
           identity remains the same.

        CHEMICAL CHANGES:


         The  changes  that  take  place  in the  chemical properties  of  a  substance  due  to molecular
           changes and new substances are formed. E.g., burning wood, rotten fruits, and vegetables,

           fireworks, rusted iron, etc.

         Chemical changes are usually permanent, which results in the formation of new substances
           with composition and properties different from those of the original substance.

         Chemical changes are also called Chemical Reactions.
         A chemical change (chemical reaction) takes place when two substances react chemically

           to form a new substance with different chemical properties.
         The substances that undergo a chemical change are called Reactants.

         The new substances formed during a chemical change are called Products.

         A  lot  of  energy  (in  form  of  heat,  light,  sound,  etc.)  is  either  absorbed  or  released  during
           chemical changes.


































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