The electronegativity difference between chlorine and sodium in a sodium chloride NaCl molecule can be found by subtracting the electronegativity values of the two elements.Chlorine has an electronegativity value of 3.16, while sodium has an electronegativity value of 0.93. The electronegativity difference between chlorine and sodium in NaCl is:3.16 Cl - 0.93 Na = 2.23So, the electronegativity difference between chlorine and sodium in a NaCl molecule is 2.23.