Step-by-step explanation:
Just like a chemical reaction, the atoms do not change and the number of atoms on the reactant side of the reaction is equal to that on the product side of the equation. (See attached diagram)
This is why we balance chemical equations in observance to the laws of thermodynamic on the conservation of matter and energy. In chemical reaction conservation of matter is observed. The atoms involved in the reactions are merely re-arranged and become part of new chemical bonds.