I try not to use the term "thermal energy" because it was abused in high
school and I want to expunge terms that might tend to be misconceived at
the outset. Dan, is the latent heat associated with the change of state of
a pure substance "thermal energy"? How about the latent heat associated
with the change of state of an alloy? Both of these are very clearly
components of the internal energy. Why mess with what works?