1 Raised over Fort McHenry on the morning of September 14, 1814, to signal American victory over the British in the Battle of Baltimore; the sight inspired Francis Scott Key to write The Star-Spangled Banner. 2  Preserved by the Armistead family as a memento of the battle.
London dispersion forces are a type of intermolecular force. They are relatively weak. They are also called induce-dipole induce-dipole interactions. 1  Present in non-polar molecules.  Due to non-systematic electron distribution where one molecule induces a dipole on another molecule.
As a result, the strongest type of intermolecular interaction between molecules of these substances is the London dispersion force . Due to the fact that the polar bonds do not cancel in the remaining molecules, they exhibit dipole - dipole interactions: these are stronger than London dispersion forces. However, #HF# exhibits hydrogen bonding - a stronger force still that is similar to the dipole - dipole interaction - whilst #CHF_3# does not. Thus, strength of intermolecular forces between molecules of each of these substances can be expressed, in terms of strength, as: #CF_4 = OF_2 < CHF_3 < HF#.