Molecular Dipole Moment
- Molecular dipole moments give information about the separation of charges in a molecule
- The dipole moment (?) is a measure of the net polarity in a molecule and is measured in Debyes (D)
- It is a product of the charge, Q, at the end of a dipole and the distance, r, between the charge
- The greater the difference in electronegativity between the bonded atoms of the molecule, the greater the dipole moment of that molecule
- For example, in chloromethane, the C—Cl bond has a dipole moment because chlorine is more electronegative than carbon
- The chlorine atom develops a partial negative (δ-) charge
- The carbon atom develops a partial positive charge (δ+)
- Therefore, the C—Cl bond is described as a polar bond
- The dipole moment in the molecule is represented using an arrow with a plus at the end
- The plus end of the arrow represents the positive atom or end of the polar bond / dipole moment
- The arrowhead represents the negative atom or end of the polar bond / dipole moment
Molecular Dipole Moment
A dipole moment exists between C-Cl bonds due to the large difference in electronegativity between the carbon and chlorine atoms.
