As Sodium is a metal and Chlorine is a non-metal they will undergo an ionic reaction in which Sodium will lose an electron and donate it to the Chlorine atom which will gain an electron. This will create a positively charged (+1) sodium ion and a negatively charged (-1) chloride ion which will both have complete outer electron shells as a result of the ionic bond. (Diagram of both sodium atom donating electron to chlorine atom via an arrow can be shown and/or the final ions formed in squared brackets with the charges shown)