How can you determine the polarity of a molecule with more than 1 kind of bond?

Question

(Eg-CH3Cl has polar and nonpolar bonds)

Answer 1

First, you need to think about the shape of the molecule and non-bonding electrons around the central atom. In this case, the molecule is tetrahedral.

Three of the bonds are C-H bonds which are effectively non-polar. Using the electronegativities of C and Cl, you can determine the polarity of the C-Cl bond. I believe (I don't have a table with me) that Cl has a larger electronegativity, and so the C-Cl bond is polar with a net dipole moment toward the Cl atom.

Now, putting all that together, you see that you have a net dipole moment for the entire molecule toward the chlorine atom.