Another way to indicate the polarity of the bond is to
draw the bond dipole
moment. The separation of charge in a polar
covalent bond creates an electric dipole. A bond dipole is represented an
arrow.
The direction of the arrow always points the the negative end
of the bond. A "+" is placed at the tail of the arrow
to indicate the positive end of the bond. Bond dipoles are vectors. In section
5.3, we have already determined that hydrogen fluoride molecule has a polar
bond. The dipole moment for this molecule is drawn over the H-F bond and points
in the direction of the fluorine molecule.
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