Starting with the intrinsic form of each atom-connectivity species (see Fig. and Fig. ), it is possible to generate a simple atomic representation of the sites and bonders. This shift from atom connectivityan abstract conceptto a plausible molecular geometry in 3D space means that steric considerations arise. Consequently, more than one geometry for each atomconnectivity species may be possible as now isomers are defined by both atom connectivity and local and global stereoisomeric atom connectivityan abstract conceptto a plausible molecular geometry in 3D space means that steric considerations arise. Consequently, more than one geometry for each atomconnectivity species may be possible as now isomers are defined by both atom connectivity and local and global stereoisomeric details. As each aspect presents a finite number of possible structural variations, the total number of conceivable chemical structures remains countable. All structures envisaged by this procedure may not be chemically feasible, however, owing to steric demands of linking the bonding sites (and possibly the bonders, see Fig. ). If a realistic complete chemical model can be constructed for a species, then computational schemes can be employed to convert this into a 3D chemical structure. As a first step, we recommend the use molecular mechanics exploiting its explicit definitions for atom connectivity. While this process is manually feasible for smaller systems, the real power will come through automation.