In a molecule of sodium chloride, which has the chemical formula NaCl, there are two atoms: one atom each of sodium and chloride. Sodium chloride is an ionic compound formed by the reaction of the metal sodium and the nonmetal chlorine.
In the ionic bonding of sodium chloride, the sodium loses an electron to become a positive ion, while chlorine receives an electron to form a negative ion. Ionic compounds tend to have high melting and boiling points.
The molecular weight of sodium chloride is 58.44 grams per mole. You find this molecular weight by adding the atomic masses of sodium and chloride, which are 22.99 grams per mole and 35.45 grams per mole, respectively.