How can I determine the intermolecular forces of attraction?
A polar bond is when atoms have unequal attractions for electrons and so the sharing is unequal.
Electromagnetivity is the ability of an atom to attract electrons when atoms are in a compound.
To determine the electromagnetivity of an atom:
< 0.5 - Non-Polar
0.5 - 1.7 - Polar
Therefore, unequal sharing results in either a hydrogen or dipole bond.
Hydrogen bonding is just a special case of dipole-dipole interactions as hydrogen is partially positive in the molecule. When covalently bonded to a highly electronegative element, the hydrogen atom becomes so highly partial positive while the other so partial negative that a higher amount of interaction is obtain.However, keep in mind that hydrogen bonding can ONLY occur when hydrogen is covalently bonded to fluorine, oxygen and nitrogen.
A dipole-dipole interaction occurs between opposite partial charges in polar molecules. These attractions are generally weaker than hydrogen bonding.
London dispersion forces occurs in all bonds, as it's a temperorary attraction force when electrons in an atom occupy positions that form temporary dipoles. It's notable particularly in noble gases and it's the weakest of the intermolecular forces.