How do you create a half reaction for?

write the net ionic equation, which is the complete ionic equation without the spectator ions. Find the elements/molecules that change their charge in the reaction. There are two half reactions. For the one that loses charge, put that molecule plus the number of electrons needed to change it to the charge it became on the left and the final product on the right. For the molecule that gains charge put the reactant molecule on the left and the product molecule on the right with the number of electrons needed to balance it.