Molecules that have both hydrogen bond accepting and donating capabilities tend to display physical properties characteristic of higher molecular weight systems (Section C).

Type of interaction Example Magnitude (kJ mol-1)

Covalent H-H 200-800

Ionic Na+ Cl-40-400

Ion-dipole Na+ (H2O)n 4-40

Hydrogen bond H2O...H2O 4-40

Dipole-dipole SO2 SO2 0.4-4.0

Figure 1. Hydrogen bond acceptors and donators.