F- and OH- ions exhibit negative standard entropy (S) values due to their unique thermodynamic properties, which are often relative to the arbitrary zero point assigned to the formation of H+ ions. This context is crucial as entropy values can vary based on the phase of matter, with the discussion primarily focusing on aqueous solutions. The negative S values for these ions suggest that they have lower entropy compared to other species, which typically have positive values. This phenomenon is not exclusive to F- and OH-, as other ions may also display negative entropy values under specific conditions, but they are among the most commonly referenced examples in thermodynamic studies. Understanding these values requires a grasp of the underlying principles of thermodynamics and the reference points used in calculations.
