Page 59 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)
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E L E M  E N T S                                                    I  R-3.4





                       atom. This symbol defines the structure of the allotrope in terms of its Bravais lattice (crystal
                       class and type of unit cell, see Table IR-3.1) a nd the number of atoms in its unit cell. Thus,
                       iron(cF4) is the allotropic modification of iron  ( g-iron) with a c ubic (c), all-face-centred  ( F)
                       lattice containing four atoms of iron in the unit cell.




                                Table IR-3.1 Pearson symbols used for the fourteen Bravais lattices

                                System                    Lattice symbol a  Pearson symbol

                                Triclinic                      P                a  P
                                Monoclinic                     P                m  P
                                                               S b              mS
                                Orthorhombic                   P                o  P
                                                               S                o  S
                                                               F                o  F
                                                                I                o  I
                                Tetragonal                     P                 t  P
                                                                I                t  I
                                Hexagonal (and trigonal P)     P                hP
                                Rhombohedral                   R                h  R
                                Cubic                          P                c  P
                                                               F                c  F
                                                                I                c  I

                                a
                                 P, S, F, I and R are primitive, side-face-centred, all-face-centred, body-
                                centred and rhombohedral lattices, respectively. The letter C was formerly
                                used in place of S.
                                b
                                 Second setting, y-axis unique.



                       Examples:

                                    Symbol        Systematic name        Acceptable alternative name
                           1.       P n           phosphorus(oS8)        black phosphorus
                           2.       C n           carbon(cF8)            diamond
                           3.       C n           carbon(hP4)            graphite (common form)
                           4.       C n           carbon(hR6)            graphite (less common form)
                           5.       Fe n          iron(cI2)              a-iron

                           6.       Fe n          iron(cF4)              g-iron
                           7.       Sn n          tin(cF8)               a-  o r  g rey tin
                           8.       Sn n          tin(tI4)               b-  o r  w  hite tin
                           9.       Mn n          manganese(cI58)        a-manganese
                          10.       Mn n          manganese(cP20)        b-manganese
                          11.       Mn n          manganese(cF4)         g-manganese
                          12.       Mn n          manganese(cI2)         d-manganese


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