Melting point vs. particle diameter — dot marks the nanoparticle's current size, square marks the bulk-like reference, dashed line is ambient temperature.
A bulk crystal melts at one fixed temperature, but the same material shrunk down to the nanoscale melts at a temperature that depends on its size. This simulator renders two crystal lattices — a fixed bulk-like particle and a nanoparticle whose diameter you control — heating under the exact same rising ambient temperature. Because a growing fraction of a nanoparticle's atoms sit at its poorly-bonded surface as it shrinks, its melting point drops steeply below the bulk value, and the live chart traces that drop across sizes while the 3D view shows the smaller particle visibly disordering — surface first, inward last — well before its larger neighbor.