Page 78 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-5.2 C O M P O S I T I O N A L N O M E N C L A T U R E

overall name of the compound is then assembled from the names of the constituents so as to
indicate their proportions. O ne category of such compositional names is generalized
stoichiometric names (see Section IR-5.4) i n w hich the various parts may themselves b e
names of monoatomic and polyatomic i ons. F or this reason, Section IR-5.3, d evoted to the
naming of ions, i s i ncluded. Another category c onsists of the names devised for addition
compounds w hich have a f ormat of their own, described in Section IR-5.5.

IR-5.2 S T O I C H I O M E T R I C N A M E S O F E L E M E N T S
A N D B I N A R Y C O M P O U N D S

A p urely stoichiometric name c arries no information about the structure of the species
named.
In the simplest case, the species to be named consists of only one element, and the name
is formed by adding the relevant multiplicative prefix to the element name ( e.g. S 8 ,
octasulfur). This case is exemplified in Section IR-3.4.3.
When constructing a s toichiometric name for a b inary compound, one element is
designated as the electropositive constituent a nd the other t he electronegative constituent.
The electropositive constituent is by convention the element that occurs last in the sequence
of Table VI* and its name i s t he unmodified element name (Table I ). The name of the
electronegative constituent is constructed by modifying the element name with the ending
‘ide’, as explained in detail for monoatomic anions in Section IR-5.3.3.2. All element names
thus modified with the ‘ide’ ending are given i n T able IX.
The stoichiometric name of the compound is then formed by combining the name o f t he
electropositive constituent, cited first, with that of the electronegative constituent, both
suitably qualified by any necessary m ultiplicative prefixes (‘mono’, ‘ di’, ‘tri’, ‘tetra’, ‘penta’,
etc., g iven in Table IV). The multiplicative prefixes p recede the names they multiply, and are
joined directly to them without spaces o r h yphens. T he final vowels of multiplicative prefixes
should not be elided (although ‘monoxide’, rather than ‘monooxide’, i s a n a llowed exception
because of general usage). The two parts of the name are separated by a s pace in English.
Stoichiometric names may correspond to the empirical formula or to a m olecular formula
different from the empirical formula (compare E xamples 3 a nd 4 b elow).

Examples:

1. HCl hydrogen chloride
2. NO nitrogen o xide, o r n itrogen monooxide, or nitrogen m onoxide
nitrogen d ioxide
3. NO 2
dinitrogen tetraoxide
4. N 2 O 4
oxygen dichloride
5. OCl 2
6. O 2 Cl dioxygen chloride

7. Fe 3 O 4 triiron tetraoxide
8. SiC silicon carbide

* T ables numbered with a R oman numeral are collected together at the end of this book.

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