Recognize the difference between the balanced and simplified versions of the reactions. The simplified version is actually balanced in terms of ratios of reactants and products, but does not take chlorine's diatomic nature into account. The balanced equation is the correct reaction. This sounds strange, but not when you have seen what happened in the above pictorial. Since there are two cations and two anions, two NaCl are formed.
Some elements are capable of ionizing into multiple oxidation states.
Each cation produces a completely different compound because different amounts of anions combine to form its product. Elements with multiple oxidation states are distinguished from each other by roman numerals placed in parentheses to the right of the chemical symbol. Let's look how they react differently in the presence of oxygen. Both coefficients and subscripts express different types of quantity in a balanced equation. Coefficients track the proportions of species present during the course of a reaction.