# Question #5981b

Aug 30, 2016

Here's why that happens.

#### Explanation:

Carbon tetrachloride, ${\text{CCl}}_{4}$, is a nonpolar molecule because of its molecular geometry.

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 $\text{C" -"Cl}$ bond is indeed quite polar. Chlorine is more electronegative than carbon, which means that it will attract the bonding 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 $\text{C"-"Cl}$ 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 $\text{C"-"Cl}$ 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 $\text{C"-"Cl}$ bonds will cancel each other out.