1. The problem statement, all variables and given/known data I understand that the hybridization of, say, ammonia is sp3. I see that the nitrogen atom of pyridine is sp2. I don't understand why the nitrogen of pyrrole is sp2. I understand that it is aromatic and thus must be sp2. But there are three bonds and one lone pair which would normally mean sp3. How does this atom hybridize to sp2?