Organic chemistry students struggle with multiple aspects of reaction mechanisms and the curved arrow notation used by organic chemists. Many faculty believe that an understanding of nucleophiles and electrophiles, among other concepts, is required before students can develop fluency with the electronpushing formalism (EPF). An expert concept map was created to depict an understanding of nucleophiles and electrophiles ideally held by undergraduates. Second year organic chemistry students were interviewed and asked to give examples of nucleophiles and electrophiles and to identify them in reactions. A cognitive map was created to represent each student's understanding. The students' maps were compared to the expert map, revealing that students possess fragmented ideas about the structure and function of nucleophiles and electrophiles.