We calculated 7 physico-chemical properties for the 17 fourth period mono-hydrides (E-H). We used the B3LYP/DGZVP theory level for calculating such properties. Afterwards, we applied Principal Component Analysis and Cluster Analysis to the 17 hydrides. Thus, we obtained a hierarchical classification that showed the similarity relationships among the hydrides studied. Afterwards, we extracted the similarity classes from such a hierarchical classification (dendrogram) and we built up a topological basis with those classes. Then, we evaluated the topological structure of some classifications based on the sort of chemical bond that present the different hydrides of the fourth period. The results of these evaluations showed that KH is the interior of the group of ionic hydrides and that CaH appears related to some transition metal hydrides. The topological properties of the metallic group of hydrides showed that the transition metals appear related to the ionic group one hand and to the covalent group on the other hand. Finally, ZnH appeared related to the main-group hydrides of the right side of the periodic table and it did not appear related to the transition metal hydrides.