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.
London forces are the only interaction that exist between all species, including ions, polar molecules, and nonpolar molecules. London interactions between polar molecules is usually stronger than their dipole-dipole interactions. This can be seen in the trend in boiling points in HCl, HBr, and HI.