a homogenous past of the system that is in contact with other parts of the system but separated from them by a well defined boundary.
Dipole - dipole forces
are attractive forces between polar molecules, that is, molecules that have dipole moments. Are the third strongest Van de Waals attractions.
Ion- Dipole Forces
attract an ion (either a cation or an anion) to a polar molecule. Are the second strongest type of Van de Waal's forces. Hydration is one example of ion-dipole bonding (N+, Mg2+ interacting with H2O)
also called London forces, attractive forces that as a result of temporary dipoles induced in atoms or molecules. In many cases dispersion forces are comparable to or even greater than the dipole-dipole forces between polar molecules. The larger the electron cloud, the higher the dispersion forces will be.
the separation of positive and negative charges in the atom (or the non-polar molecule) is due to the proximity of an ion or a polar molecule. This is a type of dispersion force.
a special kind of bond: a dipole-dipole interaction between the hydrogen in a polar bond such as N-H, O-H, F-H and on electronegative O, N, F atom.