The Periodic Table: Its Story And Its Significance

  • Eric M. Scerri
Oxford University Press: 2006. 368 pp. £19.99, $35 0195305736 | ISBN: 0-195-30573-6

The Periodic Table by Eric Scerri is the first major English-language monograph on the history of the periodic system since Jan van Spronsen's The Periodic System of Chemical Elements (Elsevier, 1969). Like van Spronsen, Scerri tries to understand the construction of the periodic table within the context of the history of matter theories. And like van Spronsen, he insists that it results from the collective work of many chemists. Chapter 3, which begins with the early triads derived from Prout's hypothesis and presents six co-discoverers of the periodic system, provides a summary of van Spronsen's classic study. However, his superficial overview of successive notions of elements mainly reinforces some popular clichés.

At this point, Scerri departs from van Spronsen. The historical sketch just provides the background for an exposition of his philosophical views on chemistry. Scerri, the editor of the journal Foundations of Chemistry, is interested above all in the question of whether chemistry can be reduced to quantum mechanics. He resolutely opposes Paul Dirac's 1929 claim that “the underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are completely known”. The main purpose of his book is to demonstrate that the periodic system has not been reduced to physics and cannot be deduced from quantum theory.

Scerri pays attention too to the philosophical choices underlying the construction of the periodic table. The chapter on Dmitry Mendeleev's process of discovery emphasizes that Mendeleev had an abstract 'metaphysical' notion of chemical elements that he clearly distinguished from Antoine Lavoisier's view of elements as simple, concrete substances — a conceptual shift first emphasized some 20 years ago. In addition, Scerri has misunderstood the epistemological status of Mendeleev's abstract notion of the element. Far from reviving a metaphysical notion, Mendeleev did his best to promote a positive, if abstract, notion of the element. Not only did he characterize this invisible entity by an individual quantitative property — its atomic weight — but he defined it by analogy with other basic concepts of chemistry, stating that the distinction between the element and simple substance was like the distinction between atoms and molecules.

Scerri is more original in his detailed account of Mendeleev's famous predictions of unknown elements. He revises the usual success story in pointing out that Mendeleev failed as often as he succeeded. He thus discusses a question first raised by Stephen Brush: whether predictions were a decisive factor in the acceptance of the periodic system. Scerri emphasizes the importance of Mendeleev's ability to fit all the elements into the system.

The core of Scerri's argument is to be found in the chapters dealing with the evolution of the periodic system with regard to changes in atomic theory in the aftermath of Mendeleev's discovery. Here Scerri makes a plea for the autonomy of chemistry. He convincingly argues that the abstract notion of the element was crucial to rescuing the periodic system in the light of the discovery of isotopes. He also rightly notes that Niels Bohr's atomic model relied heavily on spectroscopic data, rather than on theoretical calculations. Against repeated claims that chemistry has been reduced to physics, it is always useful to keep in mind that early quantum physics was based on chemical data.

Finally, in considering a variety of visual representations of the periodic system, Scerri advocates a system known as Charles Janet's left-step table, because it rests on the concept of elements as basic substances, rather than on physical properties.

All practitioners of chemistry, from researchers and teachers to engineers, seem have an opinion about what the periodic table should look like, and many of them continue Mendeleev's work in an attempt to propose better graphic representations. Despite the standard format recommended by the International Union of Pure and Applied Chemistry in 1985, with groups numbered from 1 to 18, new tables are invented every year. In 1973, Edward Mazurs reviewed hundreds of visual representations of the table and distinguished 146 structural types. The periodic system, then, is like a monument, forever inviting new creative designs.