Forms of the Periodic Table

A good deal has been said about the periodic table in previous chapters, but one important aspect has not yet been addressed. This is the question of why so many different periodic tables have been published in textbooks, articles, and on the Internet. One may also wonder whether there exists an “optimal periodic table” and whether such a question even makes sense. Assuming it is a legitimate question, one would like to know what progress has been made toward identifying such an optimal table. Before plunging into this further aspect of chemical periodicity, at least two kinds of differences among periodic tables should be distinguished. First, there is the question of whether the table is presented as having 8, 18, 32, or even higher numbers of columns. Second, there is the question of variations among tables concerning the placement of specific elements such as hydrogen, helium, lanthanum, actinium, lutetium, and lawrencium. In a classic, though flawed, book on the history of the periodic table, Edward Mazurs included illustrations as well as references to about 700 periodic tables that have been published since the periodic table was first assembled in the 1860s. In the 45 or so years that have elapsed since the publication of Mazurs’s book, at least another 300 tables have appeared, not to mention the numerous new periodic systems posted on the Internet. The fact that so many periodic tables exist is something that requires an explanation. Of course, many of these tables may not have anything new to offer, and some are even inconsistent from a scientific point of view. But even if we were to eliminate these misleading proposals, a very large number of tables still remain. In chapter 1, we saw that there are three basic forms of the periodic table: the short form, the medium-long form, and the long form. All three convey very much the same information, although the grouping of elements with the same valence is treated differently in each of these formats.