can someone explain what resultant dipole is and how it determines if something is polar or not?

Question

I have no clue what resultant dipole is.
someone please explain it and how we use that to determine if a molecule is polar or non polar
(chem help!)

Answer 1

OK...Looking at any covalent bond, you can determine whether the bond is polar or not based on the electronegativity differences between the two atoms. Now, if you look at something like CCl4. Each C-Cl bond is somewhat polar. However the molecule itself is polar because those 4 polar bonds are arranged symmetrically around the central carbon atom. In a sense, the polar bonds all cancel each other out. It's as if you attached 4 ropes to a pole and pulled in 4 directions at once with the same force in all directions...Nothing would happen. For the molecule CCl4, there is no resultant dipole.

Now, if you had CHCl3, the polarity of the C-Cl bonds is different than the C-H bond, and so the forces (polarities) don't completely cancel out. The molecule has a net resultant dipole.

By thinking about the geometry of a molecule and the polarities of the individual bonds, you can figure out whether the molecule is polar or not....Hope this helps...