Polycyclic aromatic hydrocarbons (PAHs) are a pervasive class of anthropogenic chemicals found in the environment. Molecules within this chemical class show considerable variation in toxicity. Some class members are powerful mutagens and animal carcinogens while other molecules show no similar activity after considerable testing. For a series of cyclopenta-polynuclear aromatic hydrocarbons, epoxidated in the cyclopenta ring, semi-empirical AM1 calculations, and single point ab initio calculations using the 3-21g split valence basis set, have been performed for each carbocation that might be formed by the opening of the protonated epoxide ring. For all carbocations studied, the cationic charge is distributed throughout the molecule. If the protonated epoxide ring can open so that the nominal charge is on a CH group that is attached to the central ring in an anthrylenic core, that carbocation will be greatly favored. For carbocations of this type, the unoccupied alpha position has as much or more of the cation charge as the nominally charged CH position. The group charges, and other properties related to electrostatic reactivity clearly favor addition of nucleophiles at the unoccupied alph position for carbocations in this class. However, when the addition of small nucleophiles at both of these positions is modeled for two such examples, the results are equivocal. Modeling these molecular interactions by using a larger more polarizable target may have a significant effect on the electronic factors influencing the results.