Red_Book_2005

IR-2.8
IR-2.7 ELISIONS
In general, incompositional and additive nomenclature no elisions are made when using
multiplicative prefixes.
Example:
1. tetraaqua ( not tetraqua)
2. monoooxygen (not monoxygen)
3. tetraarsenic hexaoxide
However, monoxide, rather than monooxide, is an allowed exception through general use.
IR-2.8 NUMERALS
IR-2.8.1 Arabic numerals
Arabic numerals are crucially important in nomenclature; their placement in aformula or
name is especially significant.
They are used in formulae in many ways.
(a) As right subscripts, to indicate the number of individual constituents (atoms or groups
of atoms). Unity is not indicated.
Examples:
1. CaCl2
2. [Co(NH3 ) 6 ]Cl3
(b) As aright superscript, to indicate the charge. Unity is not indicated.
Examples:
3. Cl
4. NO þ
2 þ
5. Cu
3 þ
6. [Al(H2 O) 6 ]
(c) To indicate the composition of (formal) addition compounds or non-stoichiometric
compounds. The numeral is written on the line before the formulaofeach constituent except
that unity isomitted.
Examples:
7. Na2 CO3 ·10H2 O
8. 8WO3 ·9Nb2 O 5
GRAMMAR
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