AbstractIt is shown that van der Waals volumes of 1‐atomic fragments, c.q. hydrides, can be predicted accurately via indices denoting the number of non‐hydrogen valence electrons. The introduction of a principal quantum number dependence of orbital volumes turned out to be necessary, which led to a modified molecular connectivity model. From these fragmental indices molecular valence electron indices were derived, which are demonstrated to be accurate predictors of the molecular volume of polycyclic aromatic compounds in an additive mo