Selected thermodynamic properties of a model Cu38 nanoparticle were calculated using density-functional theory to deduce the corrosion properties of metal nanoparticles. More specifically, the metal atom surface cohesive energies of Cu38 nanoparticles in ideal and nonideal configurations were calculated and compared to the metal atom surface cohesive energies of perfect lattice flat (111) terraces and corrugated (113) terraces of "bulk" copper. The overall equilibrium reaction energies for the dissociation of water, hydrogen, oxygen, and hydroxyl on both nanoparticle and ideal low-index surfaces were calculated in order to understand and establish their potential reactivity. These results demonstrate that nanoparticles are: (i) more prone to metal atom ejection than their macroscopic counterparts, and (ii) more reactive toward water and oxygen. The implications of these results toward corrosion and the ability to support cathodic electron-transfer reactions are discussed.