Dipole-dipole attractions exist between molecules that are polar. This requires the presence of
polar bonds and an unsymmetrical molecule. These molecules have a permanent separation of
positive and negative charge. In the illustration the H and of HCl is permanently slightly positive
charge. The Cl end of HCl has a permanent slight negative charge. The H atom in one molecule is
attracted to the Cl in a neighbour. The intermolecular force is weak compared to a covalent bond, but
this dipole-dipole interaction is one of the stronger intermolecular attractions.