Dipole-Induced Dipole Interactions (College Board AP Chemistry)

• This is a weak attraction that results from the interaction between a polar molecule and a nonpolar molecule
• The polar molecule induces, or causes, a temporary dipole in the nonpolar molecule by distorting its electron distribution
• For example, in the interaction between polar water molecules and nonpolar iodine molecules:
  • There is a partial negative charge on the oxygen atom of the polar O—H bond in water
  • This causes a distortion in the electron cloud distribution in the iodine molecules
  • This distortion creates an induced dipole in the iodine molecule
• This induced dipole is then weakly attracted to the negative oxygen atom, allowing some degree of iodine dissolution in water
• However, because this force is weak, the iodine molecules are not very soluble in water
  • If the water becomes supersaturated with iodine, then there are not enough water molecules to cause this attraction

Dipole-induced dipole interactions

Dipole-induced dipole interaction between polar water molecules and iodine molecules

• The strength of this interaction is dependent on two factors:
  • The magnitude of the dipole moment in the polar molecule
  • The polarizability of the nonpolar molecule