The numerical multiplier (or multiplying affix) in

IUPAC nomenclature IUPAC nomenclature is a set of recommendations for naming chemical compounds and for describing chemistry and biochemistry in general. The International Union of Pure and Applied Chemistry (IUPAC) is the international authority on chemical nomenc ...

indicates how many particular

atom Atoms are the basic particles of the chemical elements. An atom consists of a atomic nucleus, nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished fr ...

s or

functional group In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...

s are attached at a particular point in a

molecule A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...

. The

affix In linguistics, an affix is a morpheme that is attached to a word stem to form a new word or word form. The main two categories are Morphological derivation, derivational and inflectional affixes. Derivational affixes, such as ''un-'', ''-ation' ...

es are derived from both

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

and

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

Compound affixes

The prefixes are given from the least significant decimal digit up: units, then tens, then hundreds, then thousands. For example: :548 → octa- (8) + tetraconta- (40) + pentacta- (500) = ''octatetracontapentacta-'' :9267 → hepta- (7) + hexaconta- (60) + dicta- (200) + nonalia- (9000) = ''heptahexacontadictanonalia-''

The numeral one

While the use of the affix ''mono-'' is rarely necessary in

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

, it is often essential in

inorganic chemistry Inorganic chemistry deals with chemical synthesis, synthesis and behavior of inorganic compound, inorganic and organometallic chemistry, organometallic compounds. This field covers chemical compounds that are not carbon-based, which are the subj ...

to avoid ambiguity: carbon oxide could refer to either ''

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

'' or ''

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

''. In forming compound affixes, the numeral one is represented by the term ''hen-'' except when it forms part of the number eleven (''undeca-''): hence :241 → hen- (1) + tetraconta- (40) + dicta- (200) = ''hentetracontadicta-'' :411 → undeca- (11) + tetracta- (400) = ''undecatetracta-''

The numeral two

In compound affixes, the numeral two is represented by ''do-'' except when it forms part of the numbers 20 (''icosa-''), 200 (''dicta-'') or 2000 (''dilia-'').

Icosa- ''v.'' eicosa-

IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...

prefers the spelling icosa- for the affix corresponding to the number twenty on the grounds of

etymology Etymology ( ) is the study of the origin and evolution of words—including their constituent units of sound and meaning—across time. In the 21st century a subfield within linguistics, etymology has become a more rigorously scientific study. ...

. However both the

Chemical Abstracts Service Chemical Abstracts Service (CAS) is a division of the American Chemical Society. It is a source of chemical information and is located in Columbus, Ohio, United States. Print periodicals ''Chemical Abstracts'' is a periodical index that provid ...

and the Beilstein database use the alternative spelling ''eicosa-''.

Other numerical prefix types

There are two more types of numerical prefixes in IUPAC organic chemistry nomenclature. IUPAC Blue Book, 2013

Numerical terms for compound or complex features

Numerical prefixes for multiplication of compound or complex (as in ''complicated'') features are created by adding ''kis'' to the basic numerical prefix, with the exception of numbers 2 and 3, which are bis- and tris-, respectively. An example is the IUPAC name for DDT.

Multiplicative prefixes for naming assemblies of identical units

Examples are

biphenyl Biphenyl (also known as diphenyl, phenylbenzene, 1,1′-biphenyl, lemonene or BP) is an organic compound that forms colorless crystals. Particularly in older literature, compounds containing the functional group consisting of biphenyl less one ...

or terphenyl.

Etymology

"mono-" is from

''monos'' = "alone". "un" = 1 and "nona-" = 9 are from

. The others are derived from Greek numbers. The forms 100 and upwards are not correct Greek. In

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

, ''hekaton'' = 100, ''diakosioi'' = 200, ''triakosioi'' = 300, etc. The numbers 200-900 would be confused easily with 22 to 29 if they were used in chemistry. ''khīlioi'' = 1000, ''diskhīlioi'' = 2000, ''triskhīlioi'' = 3000, etc. 13 to 19 are formed by starting with the Greek word for the number of ones, followed by ''και'' (the Greek word for 'and'), followed by ''δέκα'' (the Greek word for 'ten'). For instance ''treiskaideka'', as in triskaidekaphobia.

Notes and references

* {{Reflist, 2 Chemical nomenclature