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SUBJECT-CHEMISTRY


                                              CHAPTER-D-BLOCK ELEMENTS


                          SUBTOPIC- Magnetic character, complex formation, colour compound
                          formation, catalytic activity,  interstitial compound and alloys.

                    KEY NOTES:

                      Most of the transition metals are paramagnetic in nature due to

                        presence of unpaired electrons. It is increases from Cs to Cr and
                        then decreases.
                      Most of the transition metals are used as catalyst because of (i)

                        presence  of  in  complete  or  empty  d-orbitals, (ii) large surface
                        area (iii) variable oxidation state (iv) ability to form complexes.
                      They form coloured ions due to presence of incompletely filled
                        d-orbitals  and  unpaired  electrons,  they  can  undergo  d-d

                        transition by absorbing colour from visible region and radiating
                        complementary colour.
                      Transition metals form complexes due to (i) presence of vacant

                        d-orbitals of suitable energy (ii) smaller size (iii) higher charge
                        on cations.
                      Basic oxides:  Sc O , TiO, Ti O , VO, V O ,MnO,FeO,CuO, CoO,NiO
                                               3
                                                                3
                                                      2 3
                                                              2
                                             2
                        Acidic oxides:  V O ,Mn O ,CrO ,OSO
                                                      7
                                                                4
                                                           3
                                             2
                                               5
                                                    2
                        Amphotic oxides: CuO, TiO , ZnO, CrO ,Cr , O ,Mn O ,MnO ,Mn O ,Fe O
                                                                             2 3
                                                                        3
                                                                                               3
                                                                                         3 4
                                                                                     2
                                                         2
                                                                                                 4
                                                                     2
                                                                  3
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