Intermolecular Bonds

Key Questions

  • Intermolecular forces (from Latin inter, meaning between or among) are the forces of attraction or repulsion that act between neighboring atoms, molecules, or ions.

  • Intermolecular bonds are caused by the attractive forces between the negative end of one molecule and the positive end of another.


    A polar molecule has a positive end and a negative end. When two polar molecules are near each other, they arrange themselves so that the negative and positive ends line up and attract the two molecules together


    A hydrogen bond is the dipole-dipole attraction between the positive ends (the H atoms) of the O-H, N-H, and F-H bonds in one molecule and the negative ends (the N, O, or F atoms) in a neighbouring molecule.

    In liquid water, for example, every water molecule can be H-bonded to four other water molecules.

    There are other, weaker, attractive forces, but dipole-dipole attractions are the strongest attractions among covalent molecules.

  • Answer:

    They are dipole-dipole forces, hydrogen bonds, and London dispersion forces.



    Two nearby polar molecules arrange themselves so that the negative and positive ends line up. An attractive force holds the two molecules together


    The H atom in an O-H, N-H, or F-H bond has a partial positive charge. The N, O, or F atoms in a neighbouring molecule have a partial positive charge.

    The dipole-dipole attractions between these charges are hydrogen bonds. Water molecules have strong H-bonds.


    At any given instant, there may be a greater electron density on one end of a nonpolar molecule than on the other. This instantaneous dipole can induce a dipole in a neighbouring molecule. This causes a weak attractive force called a London Dispersion Force.