Up for Discussion Nomenclature vs. Terminology by Bernardo Herold IUPAC is best known for its publications on chemical nomenclature. The results of more than a century’s work on chemical nomenclature can be found in several of the so-called “Color Books.” However, not all “Color Books” deal only with nomenclature as its main subject. One example is the “Gold Book” with the title “Compendium of Chemical Terminology.” But is there a difference between chemical nomenclature and chemical terminology, and if there is, are they mutually exclusive, and how? At first sight this seems to have the following simple answer: chemical nomenclature is about how to name chemical substances and terminology about explaining the meaning of terms used in Chemistry. When trying to draw an exact frontier between both concepts, one finds out, however, that the Devil is in the details and that many chemists have their own ideas about these details. The first difficulty lies in defining very precisely the term chemical nomenclature, whereas defining chemical terminology is much simpler. Terminology is indeed a much broader concept, sometimes defined in dictionaries as being “the body of terms used with a particular technical application in a subject of study, profession, etc.” and “terms” being “words or phrases used to describe a thing or to express a concept, especially in a particular language or branch of study.” One may add that a term may also be used to label a category into which one can place anything that fits the criteria defining that category. With nomenclature, the question is much more complex. In most dictionaries the entry “nomenclature” is defined as “names of any material object and other things,” and beyond that, even persons. In Chemistry’s case this would also include devices, tools, apparatus, instruments, etc.. However, most chemists do not consider these items to be under chemical nomenclature, but rather chemical terminology. If we accept the above definition of chemical nomenclature as “how to name chemical substances” we are excluding as a logical consequence, the names themselves singly or as a group. They are not chemical nomenclature but the product of its application. It would then be better to classify the names under chemical terminology. This is however quite different to what is done in other branches of Science. The term nomenclature
appears to have been used for the first time in Botany and Zoology, where it refers to names of species and their genus, based on the system created by Linnaeus. In this case the names are part of nomenclature, but not so in Chemistry. But is it possible to accept without any restriction the definition of chemical nomenclature as “how to name chemical substances”? This would mean that whatever the procedure to name a chemical substance is used, it would be called “chemical nomenclature.” This is not accepted by the majority of the Chemistry community. Therefore, a more restrictive definition of chemical nomenclature is needed. One might expect to find such a definition in one of IUPAC’s Color Books. This is not the case. There is indeed no entry in the Gold Book for the term “nomenclature.” Wikipedia, however, fills the gap with the following definition: “A chemical nomenclature is a set of rules to generate systematic names for chemical compounds.” It is however puzzling that instead of defining “chemical nomenclature” it defines “a chemical nomenclature.” The difference is subtle, but it is there. Some chemists are quite happy with this definition. One colleague suggested to add “the name given to the study and application of these rules.” Sticking to these definitions would improve clarity and order in the way chemists communicate with each other when dealing with matters concerning chemical nomenclature. But is it acceptable and necessary to restrict the meaning of the term nomenclature to such an extent? If one considers only Inorganic Nomenclature, there is indeed no contradiction between this definition and the recommendations of the Red Book’s 2005 edition “Nomenclature of Inorganic Chemistry.” There, the rules are exclusively about systematic nomenclature. The only names mentioned in the book which are non-systematic (if we disregard exceptions like water and ammonia) are mineral names. These are however explicitly excluded from chemical nomenclature by the Red Book, by saying that they “should be only used to designate actual minerals and not to define chemical composition.” Regarding Organic Nomenclature, the situation is however quite different, because many recommended names are non-systematic. Let us see in the first place how the term “systematic name” is defined. The “Blue Book,” “Nomenclature of Organic Chemistry” in its 2013 edition defines “systematic name” in a slightly circular way as “a name composed entirely of specially coined or selected syllables with or without numerical prefixes and other structural Chemistry International
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