Page 40 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-2.8 G R A M M A R

IR-2.7 E L I S I O N S

In general, i n c ompositional and additive nomenclature no elisions are made when using
multiplicative prefixes.

Example:

1. tetraaqua (not tetraqua)
2. monoooxygen ( not monoxygen)
3. tetraarsenic h exaoxide
However, monoxide, rather than monooxide, is an allowed exception through general use.

IR-2.8 N U M E R A L S

IR-2.8.1 Arabic numerals
Arabic n umerals are crucially important in nomenclature; their placement in a f ormula or
name is especially significant.

They are used in formulae in many w ays.
(a) As right subscripts, to indicate the number of individual constituents (atoms or groups
of atoms). U nity is not i ndicated.

Examples:

1. CaCl 2
2. [Co(NH 3 ) 6 ]Cl 3

(b) As a r ight superscript, to indicate t he charge. Unity is not indicated.

Examples:
3. Cl
4. NO þ

5. Cu 2þ
6. [Al(H 2 O) 6 ] 3þ

(c) To indicate t he composition of (formal) addition compounds or non-stoichiometric
compounds. The numeral is written on the line before the formula o f e ach constituent except
that unity i s o mitted.

Examples:
7. Na 2 CO 3 ·10H 2 O

8. 8WO 3 ·9Nb 2 O 5

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