  We propose a new method to identify transitions from a topological insulator
to a band insulator in silicene (the silicon equivalent of graphene) in the
presence of perpendicular magnetic and electric fields, by using the
R\'enyi-Wehrl entropy of the quantum state in phase space. Electron-hole
entropies display an inversion/crossing behavior at the charge neutrality point
for any Landau level, and the combined entropy of particles plus holes turns
out to be maximum at this critical point. The result is interpreted in terms of
delocalization of the quantum state in phase space. The entropic description
presented in this work will be valid in general 2D gapped Dirac materials, with
a strong intrinsic spin-orbit interaction, isoestructural with silicene.
