Bonding
8.3 Bond Polarity and Dipole Moment
Figure 7 Methane
The ideas of bond polarity and dipole moment play important roles in organic chemistry.
If you look at the image of methane on the right, the single most important aspect of it in
terms of bond polarity is that it is a symmetric molecule. It has 4 hydrogens, all bonded at
109.5° from the other, and all with precisely the same bond angle. Each carbon-hydrogen
bond is slightly polar (hydrogen has an electronegativity of 2.1, carbon 2.5), but because
of this symmetry, the polarities cancel each other out and overall, methane is a non-polar
molecule.