The Periodic Table: Its Story and Its Significance (review)

The history of chemistry is a complex tapestry of ideas, insights, discoveries, personalities, and mistaken paths. Many historians take the horizontal approach of examining the life and work of one researcher such as Lavoisier or Boyle. While good for showing personalities and controversies involving individuals, it provides only a snapshot of a particular time period and often neglects the larger philosophical questions and concepts of chemistry. In The Periodic Table: Its Story and Its Significance, Eric Scerri takes a vertical thread of the periodic law and follows its history over the last 200 years, discussing its fundamental scientific and philosophical underpinnings and showing the relationship of ideas and discoveries from multiple researchers and its impact on chemistry as a discipline. By doing so he is able to reveal the contributions of scientists who are often passed over.

Through this interplay of ideas, Scerri shows that much of the history of the periodic system has been a gradual progression of concepts brought about by scholarly debate and encounters with more than a few blind alleys. For example, Proust's law (that all atoms are made from hydrogen) was supported by many chemists, based on the frequent integer values of atomic weights as they were known at the time. However, the stubborn exceptions, such as chlorine, led other scientists to disagree and spurred experiments to develop more accurate values for atomic weights. This culminated in the acceptance of Cannizzaro's values at the Karlsruhe Conference of 1860, a crucial step in Mendeleyev's development of the periodic law. Scerri therefore refutes the Kuhnian model that the periodic system developed through sudden revolutionary insights, instead showing that it involved a slow and gradual series of evolutionary steps. He demonstrates that Mendeleyev's table didn't come out of nowhere, but built on the theories and mistakes of other researchers including Leopold Gmelin, Alexan-dre de Chancourtois, Alexander Newlands, and William Odling.

Scerri then examines Mendeleyev's ideas and how he published and championed his table and fought for its scientific acceptance. When his predictions for the existence of gallium, germanium, and scandium were vindicated, his model became the chief organizing principle for all of chemistry. Scerri also shows how knowledge of the atomic nucleus and electron orbital structure and the final triumph of quantum mechanics have helped reveal the causes for the underlying structure of the periodic table, although he points out how experimental data on elemental properties cannot yet be deduced solely from the quantum mechanical model.

In his final chapter on astrophysics and nucleosynthesis, Scerri discusses how the relative abundances of elemental isotopes observed in the universe have acted to establish or dismiss theories of cosmology, thereby demonstrating the usefulness of the periodic system in fields outside of chemistry. He also analyzes some of the puzzling patterns found in the periodic table that have not yet been successfully explained, such as the fact that certain trends in properties are shared between elements that do not lie in the same family or period. These include the diagonal similarities between lithium and magnesium, beryllium and aluminum, and boron and silicon as well as the even more mysterious "knight's move" similarities between zinc and tin, cadmium and lead, and so on. He also looks at further anomalies in the behavior of elements, polyatomic ions, and atomic super-clusters. Scerri suggests that perhaps our traditional two-dimensional periodic table needs a third dimension to account for these effects. He concludes that a continuum of periodic tables, from purely theoretical to practical, may be needed, such as a left-step format table, which does a better job of representing electron configurations than our traditional medium-long format table. This may not be a popular recommendation, but Scerri backs up his claim with sound reasoning.

Altogether, Scerri has written a detailed and fascinating account of the history and implications of the periodic table, a book of great worth to scholars and historians of...