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