The Periodic Round Table (Katz, Gary) - Journal of Chemical

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Chemical Education Today edited by

Book & Media Reviews

Edward J. Walsh Allegheny College Meadville, PA 16335

The Periodic Round Table by Gary Katz Periodic Roundtable. ACS Education Division and Fisher Science Education, 1997. $49.95. Available from Gary Katz, P.O. Box 156, Cabot, VT 05647. reviewed by Glen E. Rodgers

Unwrapping and lifting the Periodic Round Table out of its colorful box is an exciting experience for a professional chemist or a chemistry student. Touted as a “new way of looking at the elements”, it is certainly that—at least at first blush. The “table” consists of four sets of two finely finished hardwood discs each with the following elemental symbols and their corresponding atomic numbers pleasingly and symmetrically wood-burned into their faces. The four sets of two discs are 11⁄2, 3, 41⁄2, and 6 in. in diameter, each disc is 3⁄4 in. thick, and therefore the entire “round table” stands 6 in. high and is 6 in. in diameter at its base. The eight beautifully polished discs (represented below) are held together by center dowels that allow each to be rotated separately. 1–2 (H–He) 3–4 (Li–Be) 5–––12 (B–––Mg) 13–––20 (Al–––Ca) 21––––––38 (Sc––––––Sr) 39 ––––––56 (Y ––––––Ba) 57–––––––––88 (La–––––––––Ra) 89–––––––––120 (Ac–––––––––X) In the top and smallest set of discs, the two n s elements are placed each in its own hemisphere in an inner ring. In the second set, the (n – 1)p elements are found outside the ns elements in an outer concentric ring divided into six equal segments. Larger rings containing the 10 (n – 2)d and 14 (n – 3)f elements are found in the third and fourth sets of discs as necessary. The eight layers therefore contain the almost familiar number of elements: 2-2-8-8-18-18-32-32—only the double 2 in the beginning is different from what we expect. All together 120 elements are represented, meitnerium (109) being the heaviest named element. The symmetry of the aesthetically pleasing assembly is a reflection of the orderliness of the periodic table itself and certainly makes a handsome addition to any desktop or display case.

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A brief pamphlet describes the relationship between the traditional form of the periodic table and this wooden version. An additional insert provides some information about the controversy surrounding the names of the transfermium elements. The pamphlet maintains that the round table is “easier for beginners to understand” and “more enjoyable to use”. It certainly is enjoyable to take apart and analyze but it would seem that this is best done after thoroughly learning about the table in more traditional formats. Also touted is the fact that “each disc [1 through 8] corresponds to one period of the two dimensional chart” discussed in the pamphlet. This assertion is true, but the periods represented are not the same as those that appear in the traditional form of the periodic table with which we are all most familiar. For example, disc 3 has sodium and magnesium (the 3s elements) in the center with boron through neon in the outer concentric ring (the 2p elements). These eight elements, of course, do not correspond to either the second or third period of the traditional periodic table. [An arrangement of seven discs that would correspond to the familiar periods is known as the “pyramidal periodic table”. Here the discs would contain 2-8-8-18-1832-32 elements as expected and only 118 elements would be represented. A modified form of the pyramidal table was recently suggested by William B. Jensen of the University of Cincinnati (1)]. One advantage to the format presented in the “periodic round table” is that the traditional order of filling the subshells is generated by starting at the top disc and moving down through the structure. At each new disc, one always moves from the outside of that disc toward the center and then proceeds to the next level down. The advantages of the periodic round table are primarily twofold: (i) it is a beautifully made piece of scientific art and (ii) you can take it apart and analyze it and put it back together again. One suggestion for improvement: cut out each ring in a given disc so that the table can be taken apart and reassembled in pieces corresponding to the traditional subshells. With such a modification, the user could arrange the various discs as he or she sees fit—either as the author has arranged it here or with each level containing a traditional period of the periodic table. Literature Cited 1. Scerri, E. R. Sci. Am. 1998, 279(3), 78–83.

Glen E. Rodgers is in the Department of Chemistry, Allegheny College, Meadville, PA 16335.

Journal of Chemical Education • Vol. 77 No. 2 February 2000 • JChemEd.chem.wisc.edu