General formation principles
The names of all acids begin with the neuter noun Acidum, i n (acid). The second word in the term is an adjective derived from the stem of the Latin name of the acid-forming element. Since the noun is neuter, the adjective always agrees with it and takes the ending -um.
The main secret to correct spelling lies in choosing the right suffix. In pharmaceutical terminology, it acts as a chemical indicator: it immediately shows the element's valence (oxidation state) or the absence of oxygen in the compound.
Oxoacids
For acids containing oxygen, the rule for choosing a suffix is based on the oxidation state of the main element:
- Maximum oxidation state. The Latin suffix -ic-um is added to the chemical element's stem. In Russian, such adjectives are translated using the suffixes -н-(ая), -ев-(ая), or -ов-(ая).
- Acidum sulfuricum — sulfuric acid
- Acidum barbituricum — barbituric acid
- Acidum folicum — folic acid
- Acidum glutaminicum — glutamic acid
- Low oxidation state. In this case, the Latin suffix -os-um is used. The Russian equivalent is the ending -ист-(ая).
- Acidum sulfurosum — sulfurous acid
- Acidum nitrosum — nitrous acid
- Acidum arsenicosum — arsenous acid
Binary (oxygen-free) acids
The names of binary acids are built using a combined scheme. The prefix hydro- (indicating hydrogen) and the familiar highest-oxidation-state suffix -ic-um are simultaneously added to the stem of the acid-forming element.
In Russian translation, such names turn into a single long adjective ending in ...истоводородная (or they have traditional synonyms).
- Acidum hydrobromicum — hydrobromic acid
- Acidum hydrochloricum — hydrochloric acid
- Acidum hydrosulfuricum — hydrosulfuric acid
- Acidum hydrocyanicum — hydrocyanic acid
Origin of stems: why do names differ?
As you memorize acid names, you will notice that some sound almost identical in both languages, while others have to be learned by heart. All acids can be divided into two groups according to the origin of their names.
A. Matching stems (international names) Here the root of the word is transparent and understandable without translation:
- Acidum ascorbicum — ascorbic
- Acidum nicotinicum — nicotinic
- Acidum phosphoricum — phosphoric
- Acidum nucleinicum — nucleic
- Acidum salicylicum — salicylic
- Acidum boricum — boric (from borum, i n — boron)
- Acidum benzoicum — benzoic
- Acidum carbolicum — carbolic
- Acidum lipoicum — lipoic
B. Different stems (diverse etymology) Many organic acids received their Latin names from nouns denoting the natural source from which they were first isolated:
- lac, lactis n (milk) → Acidum lacticum (lactic)
- acētum, i n (vinegar) → Acidum aceticum (acetic)
- carbo, onis m (coal) → Acidum carbonicum (carbonic)
- citrus, i m (lemon) → Acidum citricum (citric)
- formīca, ae f (ant) → Acidum formicicum (formic)
- The inorganic nitric acid — Acidum nitricum — also belongs to mismatched stems.
Briefly: answers to topical questions
How are the Latin names of salts of oxoacids and binary acids formed?
Latin names of salts consist of the anion name in the nominative case and the cation name in the genitive case. Anion names are formed by adding standard suffixes to the roots of the Latin acid names:
- Salts of oxoacids with the highest oxidation state — suffix -as (corresponds to Russian -ate).
- Salts of oxoacids with a lower oxidation state — suffix -is (corresponds to Russian -ite).
- Salts of binary acids — suffix -id-um (corresponds to Russian -ide).
How are the Latin names of acid esters formed?
Latin names of acid esters consist of two words: the hydrocarbon radical name and the anion name.
Structure of an ester name:
- Radical (Genetivus) — acts as an independent neuter noun with the ending -ium (in the genitive case -ii).
- Anion (Nominativus) — the acid residue.
In Russian nomenclature, such names are written as a single combined word.
Examples:
- Methyl salicylate (Methylii salicylas) — methyl ester of salicylic acid.
- Phenyl salicylate (Phenylii salicylas) is the phenyl ester of salicylic acid.
- Amyl nitrite (Amylii nitris) is the isoamyl ester of nitrous acid.
To avoid confusing the suffixes: -ic-um means maximum (highest degree, more oxygen), while -os-um means sediment/low (lowest degree, less oxygen). Oxygen-free acids are always easy to identify by the prefix "hydro-", just like water (hydrogen).
Class and exam questions
How is the suffix -os-um translated?
In acid names, the Latin suffix -os-um always indicates a lower oxidation state and is consistently translated into Russian with the suffix -ist(aya). For example: nitrosum — nitrous.
Does the word Acidum decline in prescriptions?
Yes, the word Acidum is a second-declension neuter noun. In a prescription line, it is put in the genitive case (Acidi), and the adjective following it also takes the genitive form (e.g., Acidi salicylici).
What else to study on this topic
- Declension features of acid names in prescriptions (Nom. vs Gen.)
- Names of salts (anions) derived from acids with different suffixes
- Trivial names of organic acids in the pharmacopoeia
- Rules for abbreviating acid names in medical documents
Master the entire topic in the "Latin Language" course
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Other topics in the section "Chemical Nomenclature: Elements, Acids, Oxides, Hydroxides"
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