Sodium chloride, or NaCl, is an extremely polar ionic compound, according to Kent Chemistry. Sodium chloride is composed of an Na+ cation and a Cl- anion. In a simple molecule, such as NaCl, the whole molecule is polar if the bond is polar.
Patterns of electronegativity are dependent on the attraction that a bonding pair of electrons feels for a particular nucleus. This attraction depends on the number of protons in the nucleus, the distance from the nucleus and the amount of screening by inner electrons. For NaCl, both sodium and chloride are screened by the 1s, 2s and 2p electron orbitals. Chlorine, however, has a nucleus with six more protons than sodium. Electronegativity increases across a period of the periodic table because the number of charges on the nucleus increases. Sodium is at the beginning of period 3 on the periodic table, while chlorine is nearly at the opposite end. This gap illustrates the difference in electronegativity between sodium and chlorine. The higher charge attracts the bonding pair of electrons more strongly, making the molecule polar.