A new criterion for the metallicity of elements

A vast majority of elements are metallic in the liquid state. The latent heat of vapourization, ΔHv, of such elements is greater than the critical value of ∼ 42 kJ mol−1 (0.44 eV mol−) which demarcates metals from non-metals. It is shown that ΔHv can be related to the Fermi energy as well as to the Herzfeld criterion involving atomic polarizability.