CORRECTION: In the video above, I misspoke and said that you do NOT need to know the values for the difference in electronegativity that represent a polar bond and ionic bond. This is incorrect. You should know that non-polar bonds have a difference in electronegativity of less than 0.4. Polar bonds have differences of electronegativity between 0.4-1.8. Ionic bonds have differences in electronegativity greater than 1.8. For example, the C-H bond, has a difference in electronegativity of approximately 0.35 so the bond is not polar. For the C-Br bond, the difference is 0.41 which is polar.