Molecular connectivity is a branch of chemical graph theory, which, among other things, aims to compute the activities and properties of classes of molecules. Chemical graph theory employs graph concepts to encode the structure of a molecule. The concept of simple graph has been used to represent the sigma‐framework of a molecule, while the concept of pseudograph, or general graph can be used to encode the, pi‐ and non‐bonding n‐electrons in a molecule. The concept of complete graph has recently been introduced to encode the electron core of the atoms in a molecule. These same graph concepts have been used to tackle the problem of the hydrogen contribution in hydrogen depleted graphs. This problem has been solved with the introduction of a perturbation parameter. By the aid of these concepts it is possible to derive a set of graph‐theoretical descriptors, in our case, the molecular connectivity indices, with whom it is possible to model, in a rather simple way, the gap between the graph structure of a molecule and its experimental physicochemical and biological properties.