Thermodynamics - Size is everything

Bulk matter melts and freezes in a predictable manner. Not so clusters of atoms in their tens, hundreds or thousands, which have very different properties. They have no fixed melting temperature at a given pressure, but instead have melting ranges of temperature in which solid and liquid coexist. New work provides the first quantitative demonstration of how the melting temperature of such clusters depends on their size. But the pattern that emerges is highly irregular, and the challenge of finding its physical basis remains.