Fig. 7
Top-10 most frequent atom types (r = 0) in PubChem. Percentages indicate incidence of the atom type in the respective database: a Substance; and b Compound. Light gray bonds for clarification of connectivity and valence. Dashed lines indicate aromatic bonds as perceived using the aromaticity model OEAroModelOpenEye in the OpenEye Scientific Software, Inc. OEChem C++ toolkit [57].