I had a student ask why this is not referred to as hydrogen monofluoride. Similar, we call H2S hydrogen sulfide, not dihydrogen monosulfide.

Could we just call those common names, but that by IUPAC naming, it is actually hydrogen monofluoride? Or is it really just hydrogen fluoride. I have seen various answers on other websites, but curious if anyone knows the official answer.

The most common reason I've seen is that because both H and F has a single site open for bonding that there is no other combination possible (so no need for numerical prefixes).

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    $\begingroup$ Related: Why is CaCl2 called calcium chloride? $\endgroup$
    – user7951
    Sep 30, 2016 at 22:42
  • $\begingroup$ chemistry.stackexchange.com/a/59396/34388 $\endgroup$
    – DHMO
    Oct 1, 2016 at 1:41
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    $\begingroup$ VTC as duplicate. I don't think it makes sense to not close this. Not closing this would imply that we would allow one question for every single inorganic salt e.g. LiF, LiCl, LiBr, LiI, NaF, NaCl.......... MgF2, MgCl2, ........... $\endgroup$ Oct 1, 2016 at 6:23
  • $\begingroup$ Thank you all, the answer in the first post was more than sufficient. I agree, it is a duplicate $\endgroup$
    – J M
    Oct 1, 2016 at 21:07
  • $\begingroup$ One helpful thing to keep in mind (and you're clearly already keyed into this) is that IUPAC nomenclature is intended to reduce ambiguity and create consistency with rules that are as simple as possible. $\endgroup$
    – Zhe
    Oct 4, 2016 at 2:05


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