Here’s why that happens.

Carbon tetrachloride, ##”CCl”_4##, is a nonpolar molecule because of its .

In order for a molecule to be polar, it must have a net dipole moment. In the case of carbon tetrachloride, that net dipole moment is equal to zero.

Here’s why that is the case.

The ##”C” -“Cl”## bond is indeed quite polar. Chlorine is more electronegative than carbon, which means that it will attract the electrons more.

Consequently, a partial negative charge, ##delta^(-)##, will appear on the chlorine atom and a partial positive charge, ##delta^(+)##, will appear on the carbon atom.

A bond dipole moment will thus appear for each of the four ##”C”-“Cl”## bonds that exist in a molecule of carbon tetrachloride. Because these four bonds are identical, theese dipole moments will also be identical in magnitude.

Now, carbon tetrachloride has a tetrahedral molecular geometry. This means that the resultant of any three ##”C”-“Cl”## bonds will always

• be equal in magnitude
• have an opposite direction

with the fourth. In other words, no net dipole moment will exist because the four bond dipole moments that arise from the polar ##”C”-“Cl”## bonds will cancel each other out.