Question

WHICH IS THE MORE POLAR CL2 OR PCL3

Answer 1

Pcl3

Answer 2

Why is PCL3 more polar than CL2?

Answer 3

When ever you have elemental molecules, you can safely say that they are not polar. Cl2, O2, F2 etc. This is because the two atoms of the molecule are exactly alike in their ability to pull the electron pair towards themselves so overall there is no permanent dipole moment.

When you have a compound like PCl3, you have to look at the structure and see what it is. In the case of PCl3, if you draw the Lewis structure, you will see that there is a lone pair on P. This makes the molecule asymmetric. Each P-Cl bond is asymmetric, the electron pair will be attracted towards the Cl. So now you have a molecule that is asymmetric and the bonds have a dipole. So overall the molecule will be polar.
So when you have a molecule,
1. Draw the Lewis Structure.
2. If the molecular geometry is symmetric, it is not polar
3. If it is not symmetric, it is going to be polar.