The Shannon entropy in the atomic, molecular and chemical physics context is presented by using as test cases the hydrogenic-like atoms H-c, He-c(+) and Li-c(2) confined by an impenetrable spherical box. Novel expressions for entropic uncertainty relation and Shannon entropies S-r and S-p are proposed to ensure their physical dimensionless characteristic. The electronic ground state energy and the quantities S-r; S-p and S-t are calculated for the hydrogenic-like atoms to different confinement radii by using a variational method. The global behavior of these quantities and different conjectures are analyzed. The results are compared, when available, with those previously published. (C) 2017 Elsevier B.V. All rights reserved.