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SCIENCE

The Claim

In English chemical nomenclature, when a compound contains more than one cation or more than one anion, the ion names should be listed in alphabetical order (A–Z).

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The Short Version

The evidence does not support a general A–Z rule for ion names across English chemical nomenclature. Authoritative IUPAC sources consistently preserve the cation-before-anion order, while alphabetical ordering appears only in narrower contexts, such as some cases with multiple ions of the same class. As written, the claim overstates a limited convention as a universal rule.

Caveats

  • The statement omits the crucial qualifier that any alphabetizing, where prescribed, is within cations separately or within anions separately—not across the whole compound name.
  • Cation-before-anion remains the primary ordering rule for salts, so a reader could be misled into using a globally alphabetical sequence that is not standard.
  • The cited support for alphabetical ordering is context-specific and does not justify applying the rule to all English chemical nomenclature.

The Receipts

  1. Naming ionic compounds with multiple cations and anions

    Chemistry Stack Exchange

  2. Blue Book chapter P-1 - IUPAC

    IUPAC (hosted by Queen Mary University of London)

  3. BlueBookV2.pdf - Nomenclature of Organic Chemistry. IUPAC Recommendations and Preferred Names 2013

    IUPAC - Queen Mary University of London

  4. R-5.7.4 Salts and esters

    ACD/Labs (IUPAC Red Book online reproduction)

  5. Naming and Indexing of Chemical Substances for Chemical Abstracts

    Chemical Abstracts Service

  6. Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

    IUPAC

  7. complex ions - names

    Chemguide

  8. 2.2 Naming Ionic Compounds - Chad's Prep®

    Chad's Prep®

  9. Brief guide to the nomenclature of inorganic chemistry

    Pure and Applied Chemistry (De Gruyter)

  10. Naming ions and ionic compounds

    Khan Academy

+ 22 more sources — see the full list on Lenz

Filed Under

IUPAC

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