Graphitic edges and unpaired pi-electron spins

The effects of different types of boundaries on graphite fragments are cons idered as they influence the pi-electrons. From a simple resonance theoreti c argument there are proposed simple structural conditions governing the oc currence of "unpaired" pi-electron density near the edges. Predictions base d on these rules are made for a variety of edge structures. Further, the no vel resonance theoretic argument and predictions are strengthened through m ore elaborate considerations of both The valence bond and molecular orbital theoretic nature, especially for translationally symmetric polymer strips with Various types of edges.