The Quest to Put the Elements in Their Places

Dating from the mid-1800s, the periodic table took decades to develop and was critical to atomic theory and quantum mechanics

By Eric Scerri

Image: Scientific American

Editor?s note: The following, originally published with the title ?Putting the Elements in Their Places,? is the introduction to the Scientific American Classics special digital edition, ?The Quest for the Periodic Table? (December 2012). This edition compiles articles from our archive and traces efforts to form the iconic table. See other special digital editions on our Classics page.

The periodic table of the elements is one of the most important developments in modern science, although it dates from the 1860s. In addition to unifying a huge variety of chemical and physical phenomena, it contributed significantly to the development of atomic physics and eventually to the theory of quantum mechanics.

These days the periodic table has become something of a cultural icon?a meme, if you will. Web sites have spawned ?periodic tables? of anything and everything that can be classified, from fruits and vegetables to famous guitar players. YouTube videos alone featuring the periodic table number about 14,000, according to the quick search I made this past October. A Google search for the words ?periodic table? results in almost 23 million hits, which incidentally is more hits than for ?relativity theory? or ?quantum mechanics.?

But how did the periodic table spread? How did it evolve? How was it announced to scientists and the general public? What better way to explore such questions than through the pages of the world?s most popular and longest-running science magazine?Scientific American. The current volume contains a unique collection of articles on the periodic table, elements and the surrounding scientific developments. Six scientists independently made the discovery, although not all of them regarded it as a law. They were scattered across the world, from the U.S. to Russia, but nobody took much notice initially. All that began to change when the predictions made by the last of the six discoverers, Russian chemist Dmitri Mendeleev, began to materialize.

The first mention of the periodic law in the magazine is an 1876 report from a French journal announcing the confirmation of one of Mendeleev?s predictions, the existence of a element that became known as gallium, and the hope that some of his other predictions might soon follow. Reports of the discoveries of other elements predicted by Mendeleev are reproduced here, as well as many articles trying to make sense of and improve on the periodic table.

But the path toward progress was not always a smooth one. In the 1890s a new unpredicted element, argon, was discovered?and it seemed to defy successful placement in the periodic table. Some scientists even believed that the periodic table had met its downfall. Here we read the initial and baffling accounts of the new element by its discoverers, along with other experts, in addition to articles on how to interpret the new finding. Soon, however, chemists found several other completely unreactive gaseous elements, and eventually ?argon and its companions? found a place in the periodic system?they are the noble gases.

At the turn of the 20th century the field of physics began to invade the study of the periodic table thanks to the discovery of the electron, x-rays and radioactivity, among other phenomena. The few small blemishes that still remained in the periodic table, such as the need to reverse the elements tellurium and iodine, found a natural explanation in the discovery of atomic numbers and the occurrence of isotopes, both of which shape the characteristics of the nucleus. Here we read some articles by Frederick Soddy, one of the early pioneers in this study and the person who coined the term ?isotope.?

All the articles adhere to the Scientific American tradition of being intelligible both to the educated public and to expert scientists. Given the growing popularity of the periodic table among laypersons and scholars alike, this collection could not have come at a better time.

Source: http://rss.sciam.com/click.phdo?i=0f5b6d05e7c76142eae189efeecf329d

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