Why are hydrogen bonds considered a special class of dipole$-$dipole interactions?Anything involving hydrogen is specialWithin the bond, the H has a fully positive charge and the N$,$O$,$ or F has a fully negative chargeThe difference in charge between the H and the electronegative N$,$O$,$ or F makes the bond equivalent to an ionic bondMolecules with H$-$bonds are very reactiveWhen H is bonded to a highly electronegative N$,$O$,$ or F$,$ it results in a very polar bond