This work focuses on the relationship between structure and thermodynamic properties in metal nanoparticles. It is shown that the many-body character of interactions results in a dependence of interatomic distances on coordination numbers. At the particle surface, interatomic distances contract due to the unsaturation of atomic coordination shells, giving rise to relatively intense surface stresses. These, and the excess surface energy, induce a depression of the vacancy concentration respect to the bulk phase, and the emergence of pre-melting phenomena at the particle surface. (C) 2014 Elsevier B.V. All rights reserved.