What is the relationship between free energy gained by packing nonpolar versus polar groups?

The relationship between the free energy gained by packing nonpolar versus polar groups is fundamentally tied to how these groups interact with water and each other. Nonpolar groups typically aggregate in aqueous environments due to the hydrophobic effect, which is driven by the tendency to minimize the disruption of the hydrogen-bonded water network. When nonpolar molecules come together, they reduce the surface area exposed to water, leading to an increase in entropy (a more favorable arrangement for the system). This process is reflected by a more negative ΔG, indicating a release of free energy as the system moves toward a more stable state.

In contrast, polar groups interact favorably with water, forming hydrogen bonds. Their arrangement does not lead to the same significant increase in free energy release upon packing because their interactions with the solvent largely compensate and can even promote a more positive ΔG. Thus, the packing of nonpolar groups results in a larger negative ΔG because of the increased disorder associated with liberating water molecules that were previously structured around the nonpolar groups.

Therefore, nonpolar packing is characterized by a much more negative ΔG, indicating a strong thermodynamic favorability resulting from the aggregation of nonpolar entities away from water, contrasting with the behavior of polar groups.