"New" Schemes for Applying the Aufbau Principle Robert D. Freeman Oklahoma State University, Stillwater. OK 74078 Within the past six months there have appeared in this Journal two essentially identical "new" schemes'.2 for remembering how to write the electronic configuration of an a r b i t r a r i l y c h o s e n a t o m , f o r e x a m p l e , f o r Ca: lsZ2s22p63s23p64sz. Both authors emphasize the advantage over the "diagonal line" scheme often seen in first-year college textbooks. I agree with the claimed advantage. However, the "new" scheme is not reallv new. I t is trivial m a n ~ i n einto orbital notatron ( l t i . ~etc:) , of a form of the periohlc tihle proposed by Janet in 1927 (see Mazurs') and described in thrc Journal at least 40 years ago'. Frgure 1is a direct copy of the diagram proposed by Parsons'; Figure 2 is the Janet form of the rable.
This is not intended to discourage use of the "new" scheme. On the contrary, I strongly encourage use of it-but accompanied hy demonstration of the Janet form of the periodic table so that students can see very clearly why the scheme works. Actually, I would like t o see routine use of the Janet form; I have used it for many years on my office wall and believe that i t has many advantages. So do others; for example, in his survey of the dozens of forms that have heen invented for the periodic table, Mazurs recommends the Janet form (along with two other, more complex, variants.) Of course, it is difficult to use aform different from that used in the course text. As a not completely irrelevant aside, I note that this is another reason for objecting t o the new IUPAC scheme for numbering the groupslfamilies of the table. That scheme tends to canonize the currently popular form (1s block on the left and a hole after barium for the lanthanoids), despite the existence of other forms of the table that are demonstrably "better". I t is interesting to note, in Mazurss, that Mendeleev himself proposed aversion of the table very much like the currently popular "long form" and noted that i t would not be a convenient one. I thank John Gelder for producing Figure 2 on his (t)rusty Macintosh.
' Darsey, J. A. J. Chem. Educ. 1988, 65, 1036.
Parsons, R. W. J. Chem. Educ. 1989, 86,319. Mazurs, E. G. Graphic Representation of the Peridic System during One Hundred Years. Univ. Alabama: 1974; pp 93. 137. 143. Simmons, L. M. J. Chem. Educ. 1947,24,588-591. Ref 3. pp 6. 143. Figure 1. Parsons' scheme: read len to right, top to bottom; Dsrsey's scheme is effectlveiy identical.
Periodic Table of the Elements
Figure 2. Modern version of the Janet form ot Me periodic table (1927).
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Journal of Chemical Education
