Can chemical compounds be pluralized?

I wanted to extract a paragraph from an earlier post and open it up for further discussion.  When I was creating the chemistry dictionary file, one of the last things I did was apply the dictionary file to ASAPs of popular ACS journals.  Here’s what I wrote:

One of the biggest things I noticed during this vetting was the use of plurals in scientific writing.  Cyclopentenone is an actual compound and is in the dictionary.  If your research requires you to make a family of cyclopentenones, then the plural was probably not in the dictionary (it is now, though).  Although, that raises an interesting question: can you pluralize compounds like that?  Or is it more correct to say that a library of cyclopentenone derivatives was made?  Same thing with families of natural products.  Are they members of the brevetoxins?  Or are they more correctly members of the brevetoxin family of natural products?  I’m not sure I know the answer to that one.  One thing I do know is that I did not include plurals of elements.  Your 13C NMR doesn’t tell you that you have 2 carbonyl carbons.  It tells you that you have 2 carbonyl carbon atoms.

The ACS style guide (at least the 2nd edition) doesn’t comment explicitly on the use of plurals with chemical compounds.  What say you?


  1. It probably isn’t appropriate for scientific writing to have plural compounds and elements. Although, I find myself saying compounds in the plural form when speaking. Perhaps it is only a mater of time until it becomes common to write it that way?

  2. As far as common practice goes: it seems that when we talk about a specific molecule we keep it singular e. g. platensimycin (although there is more than one in the flask 🙂 and when it’s a class we pluralize like we talk about bulk hexanes.

  3. I agree with Mitch, it is too vague to say to simply pluralize (or pluralize simply). To write “a series of aryl-substituted cyclopentenones” is probably ok, but “a series of cyclopentenones” is not sufficient. Obviously, the more information one can provide without being verbose, the better. I think a general rule for the grey area could be as follows: If you remove the plural “s”, the word needs to still be precise and accurate.
    Taking azmanam’s case: “A family of cyclopentenones”- removing the s provides cyclopentenone, which would likely be an accurate description of only 1 member of the family. “A family of cyclopentenone derivatives”- provides cyclopentenone derivative, which would describe each family member accurately.

    /not an authority

  4. Of course functional groups and functionalities are pluralized. You wouldn’t give a second thought to writing “amides” or “alcohols” or “esters” when describing the plural, would you? Nor would you think ‘triazoles’ or ‘anthralyes’ are out of the question, I assume. How else would you say “I prefer Gramicidins A and B” without pluralizing Gramicidin? I frankly don’t find it a worthwhile endeavor to massage a sentence in a paper to carefully avoid a simple ‘s’ at the end of a compound or family of compounds. That’s how you end up with scientific literature that sacrifices clarity of thought in exchange for aureate hyperbole.

  5. I don’t think there’s any reason to be ridiculously anal with wording in cases where plurals are easily understood. Journal articles are better off with less prolixity–just use the plural.

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