In this work, the topology of the ab initio electronic density charge, using the theory of atoms in molecules (AIM). developed by Bader, is studied for the n-C4H11 species, the protonated n-butane. The electronic delocalization that operates through the sigma bonds in saturated molecules and specifically in protonated alkanes is studied by means of analysis of the charge density and the bond critical points. This analysis is used in order to establish a relationship among the parameters that determine the stability order found for the different species and relate them with the carbonium ions structure. Comparing these results with the i-C4H11 allow us to study the nature of the 3c-2e bonds in alkanes in greater detail, permitting the description on the a basicity and reactivity scales in terms of structural parameters of the carbonium ions.