What is a Polar Covalent Bond?

A polar covalent bond is a bond between two non-metals with different electronegativities. Only bonds between the same elements are truly nonpolar. The higher the difference in electronegativity, the more polar the bond is. Take a look at this table of electronegavities and let's try some examples.

http://chemistry.tutorpace.com/polar-covalent-bond-online-tutoring

consider the following bonds. They are arranged in order of increasing polarity:

Cl-Cl
H-C
H-Cl
H-O
H-F

We calculate the difference in electonegativity for each. I will use the absolute value because the sign is not important. The more electronegative atom is the negative side of the bond.

Cl-Cl 2.55 - 2.55 = 0 it's not polar at all.

H-C 2.1 - 2.55 = 0.45 it's barely polar

H-Cl 2.1 - 3.16 = 1.06 more polar

H-O 2.1 - 3.44 = 1.34 more polar again

H-F 2.1 - 3.98 = 1.88 more polar than the rest