In 1865 another chemist presented Kekule’s discovery to the Chemical Society in Paris. At the time, chemists debated the existence of atoms; they had no inkling of electrons. They knew particles came together into molecules, and that the shapes of molecules mattered to the resulting material, but how and why fueled fierce controversy.[i]
Wet reactions in the lab had long ago revealed the composition of benzene—six parts carbon to six hydrogen. But this did nothing to explain its strange reactions. Kekule had been led by a previous vision of dancing figures to the idea of valence—that atoms of certain types always bond to the same number of other atoms: hydrogen to one, oxygen to two, carbon to four. He dealt with benzene by imagining alternating single and double bonds between the carbons, but that left two bonds extra. Inspired by his vision, he connected them to form a circle.[ii]
Kekule had found the key to a new world of molecules; the revelation launched a thousand chemists in search of plunder.
Benzene, like all organic molecules, depends on the special properties of carbon: It links easily to itself and other atoms, but once connected, its bonds remain relatively stable. It takes shape easily but also holds its shape — the essence of plasticity. This makes carbon ideal for forming and the reforming complex molecules living beings require — and for building new molecules in the laboratory.
Already a few lucky experimenters had grown rich off accidental products from derivatives of benzene. Kekule’s vision gave chemists the power to predict exactly how the molecule would act. Atoms left the world of ideas, of philosophic speculation, and became a set of parts to be manipulated into useful structures. No more feeling around in the dark. Chemists could finally “see” what they were doing.[iii]
But Kekule’s ring did not explain all the mysteries of benzene. It remained more stable than its shape could account for. He missed an important feature of his vision — the snake was alive, it whirled in constant motion.
In the 1930s, Linus Pauling proposed a new idea: the electrons that form the bonds never appear in a single place but shift constantly among the carbons, causing the molecule to oscillate. The ring shape in constant motion gives benzene its stability. It never takes a single form, flashing on and off like a ghost among all of its potential states. Pauling called this resonance, from the Latin word for echo.[iv]
The benzene ring vibrates in the cells of every living being: plant, animal, human and their fossilized and liquefied remains—coal and oil. Ripped and scraped out of earth, coal fueled the smoking factories; benzene split from coal fueled the labs, giving rise to entirely new species of molecules.
Chemists bolted these creatures together, and out of their test tubes came dyes, drugs, pesticides, explosives — and something else, a new material. It could be melted and molded, transformed by heat and pressure into an object — any object — millions of identical objects — impervious to flame, corrosion, electricity, water, or any other force. Its first trademark symbol: infinity.[v]
[ii] Image and Reality, 196, “Nanoaesthetics,” 3-4
[iii] Image and Reality, 211, 297
[iv] Istvan Hargittai, Judging Edward Teller: A Closer Look at one of the Most Influential Scientists of the Twentieth Century (Amherst, New York: Prometheus Books, 2010), 114-115.
[v] Jeffrey L. Meikle, American Plastic: A Cultural History (New Brunswick, NJ and London: Rutgers University Press, 1997), 1, 31-62