Four different types of reaction

        1.  Synthesis
                bringing together
                2H₂  +   O₂  ---->   2H₂0
                plus sign (+)  on the left

        2.  Decomposition
                breaking apart
                2H₂O₂  --->   2H₂O    +   0₂
                plus sign(+) on the right

        3.  Replacement
                elements replace other elements
                Fe   +   CuCl₂   ----->  FeCl₂  +  Cu
                plus sign(+)  on  both sides