Here's why that happens.
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.
Consequently, a partial negative charge,
A bond dipole moment will thus appear for each of the four
Now, carbon tetrachloride has a tetrahedral molecular geometry. This means that the resultant of any three
- 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