# Why bond polarity and molecular geometry determine molecular polarity?

Take carbon tetrafluoride, $C {F}_{4}$; the $C - F$ bonds all show charge separation in that fluorine polarizes electron density towards itself (i.e. a $C - F$ bond is polar!). Nevertheless, if we take the vector sum of these individual bond dipoles, the indvidual vectors sum to zero.
The same reasoning applies to $\text{C} C {l}_{4}$, carbon tetrachloride, and $C H C {l}_{3}$, chloroform. Carbon tetrachloride is a non-polar solvent in that the bond dipoles will sum to zero (they must, because of the molecular symmetry, tetrahedral with $109.5$""^@ bond angles. On the other hand, chloroform has a degree of molecular polarity and is thus a polar solvent, inasmuch as the individual bond dipoles DO NOT sum to zero, and there is a resultant molecular polarity.