Relativistic effects in neutral atoms are analyzed, on the basis of discrepancies between the Hartree-Fock and Dirac-Fock electron charge densities. In doing so, comparative density functionals are employed as quantifiers of dissimilarity among the above densities. A detailed analysis throughout the Periodic Table reveals the relevance not only of weightiness for the systems considered, but also of their shell structure. (C) 2015 Elsevier B.V. All rights reserved.