Fig. 1: The nitration of benzene in three rows. Row 1: benzene plus the nitronium ion, NO2 plus, with an arrow marked slow, gives an intermediate. Row 2: the intermediate is drawn as three structures joined by double-headed resonance arrows. In each, one ring carbon carries both an H atom and an NO2 group, and a positive charge sits on a ring carbon: next to it in the first, opposite it in the second, and next to it on the other side in the third; the other four ring carbons carry two double bonds. Row 3: the intermediate, with HSO4 minus over the arrow and fast under it, gives nitrobenzene and H2SO4.