Chemical Education Today
Atoms versus Nuclei: Response to Logic Lessons Lost
Atoms versus Nuclei: The Author of Logic Lessons Lost Responds
I wish to thank Professor Clark for his recent contribution (1) rekindling Professor Jensen's three-part series (2-4). Clark's additional commentary will serve as a reminder for educators to pay close attention when defining chemical terms in the classroom. Unfortunately, confusion arose upon the introduction of the term atome. Clark specifically notes the improper use of the term atoms to describe nuclei within a polynuclear molecule and asks the reader: “What then do we call the C in CO2? Jensen does not say” (1). Actually, Jensen does. He specifically answers Clark's question in part two of his series when stating: “Molecules are made of nuclei and electrons and not of neutral atoms” (3, p 821). In this sense, Clark's atoms are nuclei and his atomes simply atoms. Additionally, the use of a qualifier is acceptable. These nuclei, while technically not atoms by our definition, are classified “bound atoms”. The grammatical modifier tells the reader that we are not dealing with neutral atoms, but rather atoms that have been invariably changed. Because “bound atoms” are inherently different from neutral atoms, future chemists will get to keep atoms in their lexicon. Instead of introducing a new term, I suggest the following:
I am pleased to reply to Michael Matson's criticism (1) of my “Logic Lessons Lost” commentary (2). William Jensen (3) has clearly pointed out what molecular orbital chemists have known for half a century: atoms, once reacted, should no longer be called atoms. The reason behind this is that energy changes in their electron structure mean they are no longer the atoms they once were. In my commentary under the paragraph heading Atoms, I briefly summarized Jensen's position on atoms in molecules as opposed to free atoms, and I stated Jensen's conclusion that atoms in molecules should not be called atoms anymore (3), yet we should still call lone atoms “atoms”. Matson read this far in my commentary and agreed wholeheartedly with Jensen, repeating Jensen's conclusion that “molecules are made of nuclei and electrons and not of neutral atoms” (3). It is quite clear that Matson agrees with Jensen at this point, and it is also clear that he saw no need to rename anything. I, on the other hand, was very unhappy with Jensen's solution of “free atom equals atom” and bound atom equals “nuclei plus some fraction of the surrounding electrons”. I am a retired teacher, coauthor of two texts (one general chemistry and one physical science), and with this perspective I fail to see future textbook authors explaining to their readers why the argon in our air is made of atoms, but all the “chemicals” in lab do not contain atoms. What will the text say they contain? Will texts tell them that molecules do not contain atoms and that, before inert gases were discovered, all the elements in the periodic table contained no atoms? All the remaining elements are in a condensed phase (at STP), and thus do not contain atoms according to Jensen's word choices. If I know authors, and what they are accustomed to writing in their first chapters, I can assure you it won't be that “nuclei and an uncertain electron cloud” is what formerly was called atoms, and grouped atoms are polynuclear molecules, and their component parts have lost their “atom” label. These nuclei won't become atoms until they are liberated, free from bondage. If this is what future authors will write, then Jensen and Matson are right, and I am wrong. And so to save textbooks from a future of boringly few atoms, I have seriously proposed the atome name as a way of parking the noble gases (and any other lone neutral atom) off to one side. If we all do that, then we are free to put atoms back in our molecules, and to change our textbooks minimally. Matson is correct. I did not advocate Jensen's solution, logical though it is. I offered my own solution, which, although odd, is not as odd as the atomless chemistry that would result from Jensen's logic. All of which means that linguistically our logic must be tempered with practicality, and an admission that over the last century chemistry texts have accumulated a great inertia of ideas, as was suggested by the first section of “Logic Lessons Lost”. This inertia of ideas will be very hard to change. However, I suspect
1. Authors should be reminded to describe molecules as what they are composed FROM as opposed to what they are composed OF.
• While incorrect to say that CO2 molecules are made of carbon and oxygen atoms, we can accurately state that they are made from carbon and oxygen atoms. 2. Authors should be reminded to use qualifiers of the word atom should they choose to speak of molecular composition.
• While incorrect to refer to the “carbon atom” in a CO2 molecule, it would be permissible to refer to the “bound carbon atom” in a CO2 molecule.
I strongly encourage readers of this Journal not to adopt the suggested term atome for neutral, free atoms. Literature Cited 1. 2. 3. 4.
Clark, R. W. J. Chem. Educ. 2010, 87, 901–902. Jensen, W. B. J. Chem. Educ. 1998, 75, 679–687. Jensen, W. B. J. Chem. Educ. 1998, 75, 817–828. Jensen, W. B. J. Chem. Educ. 1998, 75, 961–969. Michael L. Matson Department of Chemistry, Rice University, Houston, Texas 77005, United States
[email protected] DOI: 10.1021/ed100878j Published on Web 02/14/2011
r 2011 American Chemical Society and Division of Chemical Education, Inc.
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Chemical Education Today
that textbook authors could stand for argon to be atomes if they could still have their magnesium oxide (and almost everything else) made of atoms. And speaking of modernizing textbooks, Craig F. Bohren, writing about physics textbooks, expressed this opinion in his recent article entitled “Physics Textbook Writing: Medieval, Monastic Mimicry” (4): The best advice to anyone who would write a physics textbook, especially an introductory textbook, is to adopt the working hypothesis that everything in previous textbooks is wrong. But that is not what is usually done. Like a medieval monk cloistered in a cell decorating illuminated manuscripts but leaving dogma intact, the writer of textbook N dutifully copies what is in textbook N - 1, adding a few arabesques but blithely transmitting errors unto the Nth generation.
Of course authors of chemistry books aren't guilty of this, but there is a tendency to stasis in chemistry textbook writing. New authors beware. Literature Cited 1. 2. 3. 4.
Matson, M. L. J. Chem. Educ. 2011, 88; DOI: 10.1021/ed100878j. Clark, R. W. J. Chem. Educ. 2010, 87, 901–902. Jensen, W. B. J. Chem. Educ. 1998, 75, 817–828. Bohren, C. F. Am. J. Phys. 2009, 77, 101–103. Roy W. Clark Department of Chemistry, Middle Tennessee State University, Murfreesboro, Tennessee 37130-4531, United States
[email protected] DOI: 10.1021/ed100920p Published on Web 02/09/2011
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