One is the attractive force between opposite charges of polar molecules. It is stronger than London forces but much weaker than ionic forces in ionic solids. Molecular solids and liquids with this type on bonding generally have higher melting points. Some compounds appear to have abnormally high melting points when compared to compounds of similar size, shape, and total electrons. In many of these cases, such compounds exhibit hydrogen bonding, involving highly electronegative nitrogen, oxygen, or fluorine atoms.
Water is an example of a hydrogen-bonded substance.
This can also be reinforced using appropriate cut-outs on a flannel board or on the overhead projector. There are three important types of collisions. Ha collides with the molecule. If Ha sticks to Hb, then Hc will be ejected from the other end and a new molecule, Ha-Hb will result.