Content morphemes

At this point, it might be useful to mention that morphemes could be divided into two classes: content morphemes (i.e. those that have independent meaning) and functional morphemes. All content words contain at least one content morpheme. In English, content words include nouns, adjectives, adverbs and most verbs, while functional morphemes include conjunctions, prepositions, pronouns and articles as well as affixes. These two classes are sometimes referred to as “open class” and “closed class”, respectively. New morphemes are easily added to the former and hardly ever to the latter.

Now to continue with the list that I started earlier.

6. Since chemical names consist of content words (ii), they are open-class.
7. Every content word contains at least one root (iv) which is a content (open-class) morpheme.
8. Affixes are functional (closed-class) morphemes.
9. New chemical names are formed by combining existing content morphemes with functional morphemes or adding new content morphemes.

OK? Still no objections?

Here’s one more statement.

10. Most systematic English chemical names contain roots that came from Greek or Latin.

When I say “most” I mean more than a half, although I suspect the proportion of names based on Greco-Latin roots is much higher than 50%. By the way, this is true for English scientific terminology in general. Just saying. Maybe this can help us to figure out which of “prefixes”, “suffixes” or “endings” used in chemical nomenclature are genuine prefixes, suffixes or endings.

Having a word part of Greek or Latin or any other “foreign” origin does not necessarily mean it should behave as it does in their respective languages. I’ve already mentioned that the name “neon” inflects in Latin as a neuter second-declension noun with the root ‘ne’, while in other languages ‘neon’ is a root. This can be seen in words such as “neonium” or “neonide” although the term “neide” also has been used.

On the other hand, English “sulfur” is borrowed from Latin where it inflects as a neuter third-declension noun with the root ‘sulfur’. This did not prevent English and many other languages to adopt terms such as “sulfate”, “sulfide”, “sulfonic” etc. based on the clipped root ‘sulf’.

Content morphemes could be shortened even further without losing their meaning. For instance, the term “aldehyde” was coined in 1835 by Justus von Liebig as a contraction of the Latin phrase alcohol dehydrogenatus, i.e. “dehydrogenated alcohol” [1]:

R–CH2–OH	→	H2	+	R–C(=O)H
alcohol	→	dihydrogen	+	aldehyde

In its turn, “alcohol” comes from the Arabic الكحل (al-kuḥl), where ‘al-’ is just a definite article. Both ‘alcohol’ and ‘aldehyde’ behave like roots (alcoholate, benzaldehyde), while the “suffixes” ‘-ol’ (ethanol, phenol) and ‘-al’ (pentanal, retinal) are their corresponding splinters. Nevertheless, there is no confusion as to meaning of ‘-al’ in organic names even though it is a descendant of an article, a morpheme with next-to-zero semantic load.

What if the word with more than one content morphemes loses one of them? The word hydrogène was introduced in Méthode de nomenclature chimique [2] as a combinaton of the Ancient Greek root ‘hydr’, from ὕδωρ, “water”, and French -gène “producing”, ultimately also from Greek -γενής. Thus “hydrogen” literally means “water-producing”. The problem is, the word is too long while hydrogen atoms are very common. And so hydrogen as such nowadays is only used to name elementary hydrogen substances such as monohydrogen (H•), dihydrogen (H₂), trihydrogen(1+) (H₃⁺), and in the names of reactions, viz. hydrogenation and dehydrogenation^*. In the rest of chemical names, morphemes for hydrogen atoms got shortened by losing the — meaningful! — ‘gen’ bit. Since ‘hydr’ already had the meaning “water”, the use of ‘hydr’ in the sense “hydrogen” was bound to cause confusion. Anyone who’s ever mistaken carbohydrates for hydrocarbons will know what I mean.

Morpheme	Meaning	Example
anhydride	compound derived by the formal loss of water from an acid	benzoic anhydride
anhydro-	formal loss of a water molecule from the parent structure	3,6-anhydro-α-L-galactopyranose
dehydro-	unsaturation of carbon—carbon bonds with loss of (even number of) hydrogen atoms	1,2-didehydrobenzene
hydrate	addition compound containing water as a component	copper(2+) sulfate pentahydrate
hydride (1)	hydrogen anion, H−	hydride
hydride (2)	compound of hydrogen	lithium hydride
hydrido-	hydrogen ligand, —H	trihydridosulfur(1+)
hydro-	addition of (even number of) hydrogen atoms to unsaturated carbon—carbon bonds	1,2,3,4-tetrahydronaphthalene
hydron	hydrogen cation, H+	hydron

*	It was also used in Liebig’s “dehydrogenated alcohol”. However, in “aldehyde” even the ‘r’ of ‘hydr’ is lost.

References

1. Liebig, J. (1835) Sur les produits de l’oxidation de l’alcool. Annales de Chimie et de Physique LIX, 289—327.
2. Guyton de Morveau, L.-B., Lavoisier, A.-L., Berthollet, C.-L., Fourcroy, A.-F., Hassenfratz, J.H. and Adet, P.A. Méthode de nomenclature chimique. Cuchet, Paris, 1787.