In a sodium chloride NaCl molecule, there is only one atom of sodium and one atom of chlorine. The chemical bond formed between sodium and chlorine is an ionic bond. This bond is determined by the difference in electronegativity between the two atoms.Sodium Na is a metal with an electronegativity of 0.93, while chlorine Cl is a non-metal with an electronegativity of 3.16. The difference in electronegativity between sodium and chlorine is 3.16 - 0.93 = 2.23. Generally, if the electronegativity difference between two atoms is greater than 1.7, an ionic bond is formed.In an ionic bond, one atom sodium in this case loses an electron to become a positively charged ion cation , while the other atom chlorine gains an electron to become a negatively charged ion anion . The electrostatic attraction between the positive and negative ions holds the compound together. In the case of NaCl, sodium loses one electron to form Na+ and chlorine gains one electron to form Cl-, resulting in an ionic bond between Na+ and Cl-.