# How do you determine the bond polarity between two atoms?

In order to determine the bond polarity between two atoms, their respective electronegativities must be determined. Electronegativity is the tendency of a bonded atom to attract bonded electrons to itself. The difference in electronegativity, $\Delta \text{EN}$, can help predict the bond type. In general, a $\Delta \text{EN}$ of < 0.4 indicates a nonpolar bond, while a $\Delta \text{EN}$ of 0.4 - 1.7 indicates a polar covalent bond, and a $\Delta \text{EN}$ > 1.7 indicates an ionic bond. https://www.chem.wisc.edu/deptfiles/genchem/sstutorial/Text7/Tx71/tx71.html
For the C-H bond, the $\Delta \text{EN}$ = $\text{2.55 - 2.20 = 0.35}$. This is a nonpolar bond because a $\Delta \text{EN}$ of less than 0.4 is indicative of a nonpolar bond.
For the C-Cl bond, the $\Delta \text{EN}$ = $\text{|2.55 - 3.16|" = |0.61|}$ ($\Delta \text{EN}$ is an absolute value; it is never negative.) The $\Delta \text{EN}$ of 0.61 indicates that the C-Cl bond is polar covalent.