Compare the electronegativities of the two atoms
If the electronegativity difference is very small or zero, the bond is nonpolar
If the electronegativity difference is moderate or large, the bond is polar
Bonds between identical atoms are nonpolar
Bonds between different atoms can be polar if one atom attracts electrons more strongly
A difference of about 0.0 to 0.4 usually indicates a nonpolar covalent bond
A difference of about 0.5 to 1.7 usually indicates a polar covalent bond
A difference greater than about 1.7 usually indicates an ionic bond rather than a polar bond
Check whether the electrons are shared equally or unequally
Equal sharing means nonpolar
Unequal sharing means polar