Benzene

The structure of the benzene molecule proved to be a challenge for chemists for more than 40 years after the compound's discovery by Faraday. Its formula suggests the existence of multiple double and/or triple carbon-carbon bonds, because there are too few hydrogen atoms for six single-bonded carbon atoms. However, benzene exhibits none of the chemical properties associated with such a structure, the property of addition, for example. That problem was largely solved in 1865 by the German chemist Friedrich August Kekulé. Kekulé's own story is that he fell asleep in front of his fireplace and dreamed of a snake with its tail in its mouth. He awoke to the realization that the benzene molecule might be a ring consisting of six carbon atoms, with one hydrogen atom attached to each carbon atom. That general structure is still accepted today, although the concept of resonance has replaced that of simple single and double bonds between adjacent carbon atoms in the benzene ring.