I am working on chemistry papers and I came across the term "a Mg salt".

I am unsure if chemical elements are read out as their constituent letters (for example, "em gee" for Mg) or if you read them out as the element they represent (magnesium).

Should this term be "an Mg salt" or not? What about compounds with formulas, such as oxides? (e.g., "a Na2O container", "a sodium oxide container")

Thank you.

Clarification: I am interested in knowing if I should use "a" or "an" in written documents. I do not care much about how these terms should be read out in conferences, but feel free to leave comments about that too.

I am editing papers, so the question would be along the lines of if "an Mg salt" would be incorrect usage of the indefinite article in a written document.

  • 5
    I read element symbols as though the name of the element was written out, and use the proper article on that basis. Thus, "a Mg salt" or "a Na oxide" are correct, because they're "a magnesium salt" or "a sodium oxide". It's also "a U fluoride", because the pronunciation of "uranium" starts with a consonantal "y" sound. Jan 25, 2018 at 15:34
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    Yes; the only time I would read the symbol as a symbol ('emm gee') is when I'm specifically talking about the symbol rather than the underlying element, or when I'm reading a formula - "Ethanol is see two aitch five oh aitch". Jan 25, 2018 at 15:44
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    @JeffZeitlin that sounds correct and reasonable, but in this video the speaker refers to NaCl initially as "sodium chloride", then subsequently "enn-ay-see-ell". So perhaps you can do it either way. youtube.com/watch?v=ZIIjMe2kzk4 UPDATE - just saw your second comment where you cover this :) Jan 25, 2018 at 15:46
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    You would usually say the whole word ("magnesium salt"). But it's totally commonplace to say (for example) "h 2 o" rather than "water". Saying "m g salt" would be totally normal and OK.
    – Fattie
    Jan 25, 2018 at 16:14
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    As a Licentiate of the Royal Society of Chemistry, I would never write 'a/n Mg salt'. I would regard it as unprofessional and it was never done so in the papers I used to read back in the day. It is a magnesium salt. The chemical symbol is about the chemistry of the salt, MgCl2 or whatever. 'Magnesium salt' is about English wording.
    – Nigel J
    Jan 25, 2018 at 16:15

2 Answers 2


The following advice, found in an article by Michaela Panter, PhD, gives the advice found in the ACS style guide, but other science-related style guides often echo this:

Should the pronunciation of an element’s full name or its symbol be used to choose an indefinite article?

The American Chemical Society (ACS) style guide states that the full element name, rather than its abbreviated form, should be considered when choosing whether to use a or an. Therefore, “a Ag nanoparticle” is correct because this phrase is read as “a silver nanoparticle,” where “silver” begins with a consonant sound; pronouncing the phrase as “ay-gee nanoparticle,” which would merit the use of an due to the vowel sound “ay,” is less standard. Here are two additional examples:

A Li battery (“Li” is pronounced “lithium,” which begins with a consonant sound)

An Ar laser (“Ar” is pronounced “argon,” which begins with a vowel sound)

There obviously seems to have been a move away from the insistence on the word rather than the symbol in running text in scientific articles in recent years.

  • Edwin, it sounds like actually OP is asking about written comms. I too thought OP meant spoken form.
    – Fattie
    Jan 25, 2018 at 18:48
  • Your last example would often be "an Ar+ laser", pronounced "an argon ion laser". Scientists are no more logical than the rest of humanity.
    – Chris H
    Jan 25, 2018 at 20:41

My first degree was chemistry and I taught biochemistry for many years. I could not have imagined anyone writing “an Mg” as I have never heard anyone say anything other than “magnesium”. To my amazement a Google ngram search showed some people actually do write this. However they are in the minority.

As regards “a/an Na2O container”, my advice is don’t either say it or write it if you can spell it out in words. It is clumsy and ugly. This is consistent with the comment @Nigel_J made about writing “magnesium salt” rather than “Mg salt”.

In summary, you seem to be focusing on technical minutiae rather than clear communication. I suggest that you change lenses.

  • David (and @Nigel J), this was my initial reaction to this question too (and I actually contributed to a paper once, long ago). However, researching (as all good scientists must do) (I always wanted to be one), I've found that academic scientific style guides mainly accept strings like 'a Mg salt'. Things change. Jan 25, 2018 at 20:54
  • @EdwinAshworth — Yes, if you are writing for a journal you have to play by their rules, and often they are driven by space considerations or the chemicals are so complex they have to use the formula. In my nick of the woods the subjects of pedantry were different: RNAase or RNase for ribonuclease, apostrophes in plurals of capitalized acronyms (RNAs or RNA's). Yawn.
    – David
    Jan 25, 2018 at 21:26

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