Page 13 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

G E N E R A L A I M S , F U N C T I O N S A N D M E T H O D S I R-1.5

IR-1.4 F U N C T I O N S O F C H E M I C A L N O M E N C L A T U R E

The first level of nomenclature, beyond the assignment of totally trivial names, gives some
systematic information about a s ubstance b ut does not allow the inference of composition.
Most of the common names of the oxoacids (e.g. sulfuric acid, perchloric acid) and of their
salts are of this type. Such names may be termed semi-systematic and as long as they are
used for common materials and understood by chemists, they are acceptable. However, it
should be recognized that they may hinder compositional understanding b y t hose w ith
limited chemical training.
When a n ame i tself allows the inference of the stoichiometric formula of a c ompound
according to general rules, it becomes truly systematic. Only a n ame a t t his second level of
nomenclature becomes suitable for retrieval purposes.
The desire to incorporate information concerning the three-dimensional s tructures of
substances has grown rapidly a nd the systematization of nomenclature has therefore had
to expand to a t hird level o f s ophistication. Few chemists want t o u se such a d egree o f
sophistication every t ime they refer to a c ompound, but they may wish to do so when
appropriate.
A f ourth level o f n omenclature may be required f or the compilation and use of extensive
indexes. Because the cost to both compiler and searcher of multiple e ntries for a g iven
substance m ay be prohibitive, it becomes necessary t o d evelop systematic hierarchical rules
that yield a u nique name for a g iven substance.

IR-1.5 M E T H O D S O F I N O R G A N I C N O M E N C L A T U R E

IR-1.5.1 Formulation of rules
The revision of nomenclature is a c ontinuous process as new discoveries make
fresh demands on nomenclature systems. IUPAC, through the Division of Chemical
Nomenclature and Structure Representation (formed in 2001), studies all aspects of the
nomenclature of inorganic a nd other substances, recommending the most d esirable practices
to meet specific p roblems, for example for writing formulae and generating names. New
nomenclature rules need to be formulated precisely, to provide a s ystematic basis for
assigning names and formulae within the defined areas o f a pplication. As far as possible,
such rules should be consistent with existing recommended nomenclature, in both inorganic
and other areas of chemistry, and take into account emerging chemistry.

IR-1.5.2 Name construction
The systematic naming of an inorganic s ubstance i nvolves the construction of a n ame
from entities w hich are manipulated in accordance w ith defined procedures t o p rovide
compositional and structural information. The e lement names (or roots d erived from them or
from their Latin equivalents) (Tables I a nd II*, see also Chapter IR-3) are combined with
affixes in order to construct s ystematic names by procedures w hich are called systems of
nomenclature.
* T ables numbered with a R oman numeral are collected together at the end of this book.

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