Would a C-Cl bond be polar or nonpolar in a molecule if both have a formal charge of 0?
I thought at first that it would be polar just due to their electronegativities (just by looking at the periodic table), but if they both have a formal charge of 0, does that make it a nonpolar bond or does formal charge not really matter?
Use their electronegativies.
Cl-Cl would be nonpolar because they will share the electrons equally.
C-Cl should be polar.
I agree with John1. Look at CCl4. In CCl4 both C and Cl have zero formal charge; however, each C-Cl bond is polar. The CCl4 MOLECULE is symmetrical; therefore, it is non-polar but that's because each of the C-Cl polar bonds cancel each other because of the symmetry of the molecule.
To determine whether a C-Cl bond is polar or nonpolar in a molecule, you need to consider both the electronegativity difference and the formal charge.
Electronegativity is a measure of an atom's ability to attract electrons towards itself in a chemical bond. Chlorine (Cl) is more electronegative than carbon (C), so in a C-Cl bond, chlorine will attract the shared electrons more strongly, creating a partial negative charge (δ-) on chlorine and a partial positive charge (δ+) on carbon. This uneven distribution of charges makes the bond polar.
However, formal charge is different from partial charges. Formal charge is a concept used to determine the electron distribution in a molecule or ion by comparing the number of valence electrons an atom should have (based on its group number on the periodic table) and the number of electrons it actually has in a specific compound. It is a formal accounting system, not a physical charge.
In the case of a C-Cl bond in which both carbon and chlorine have a formal charge of 0, this means that they have the same number of electrons as they would have in their isolated (unbonded) form. Formal charge alone does not determine the polarity of a bond.
So, even with a formal charge of 0, the C-Cl bond would still be polar due to the significant electronegativity difference between carbon and chlorine.