Single diplacement reaction

In this , more active element displaces less active element from the compound. For example if you put a piece of zinc metal into a copper(II) sulphate solution.

                                       Zn(s)  + CuSO₄ (aq)      _->   ZnSO₄ (aq)+ Cu(s)

In this case zinc replaces copper since it is more active. However if we place Copper in Zinc sulphate solution, nothing happens.When the ionically bonded copper sulphate is dissolved in water, it breaks apart into ions. The copper ion has a +2 charge because it lost 2 electrons. It's a cation, a positively charged ion.The sulphate ion has a -2 charge because it has two extra electrons. It's an anion, a negatively charged ion.

          To show the reaction:

               

                           Zn(s) + Cu²⁺(aq) + SO₄ ^2-  -> Zn²⁺ + SO₄^2- + Cu(s)

      

Notice that  SO₄ ^2- , does not change in the reaction , ions that does not change during the reaction and are found on both sides of the equation in an identical form called spectator ions. 

Thus net-ionic equation would be:

                                    Zn(s) + Cu²⁺(aq)  -> Zn²⁺  + Cu(s)