Chapter 22 Transition Metals Week 1 2009

Chapter 22 Transition Metals Week 1 2009 - CHAPTER 23 TM =...

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CHAPTER 23. The Transition Metals (TM ) TM = metals  having  partially-filled  d or  f shells  as  the  elem e nts  or  in com m on  oxidation  s We  shall look  only  at the  d metals. Orbital energies : 1s2s2p3s3p4 s 3d 4p5s4d 5p6s4f5d 6p7s5f6d. . [Ar] = 1s 2 2s 2 2p 6 3s 2 3p     1 st  TM Series:   [Ar] 4s 2 3d      (the “condensed” configuration) 2 nd  TM Series:  [Kr] 5s 2 4d                 3 rd  TM series:   [Xe] 6s 2 5d n Group number  = sum  of outer  s  and  d electrons  Fe  : group  8 : [Ar] 4s 2  3d 6 Table 22.1 . Filling  of s  and  d orbitals   -  note   stability   of   half-filled   (Cr)   and   filled   (Cu)   d   shells.   **When TM’s form M n+ ions (i.e. higher oxidation state than the element), the s/ d energies switch position (now 3d below 4s) and remaining electrons all go in d orbitals.** The   outer   electron   confign   (“partial”   configuration)   thus  now  is: Ni metal  (= Ni 0 )  = 4s 2  3d 8        but    Ni +  = 3d 9 , Ni 2+  =  3d 8  , etc Ag metal = (Ag 0 ) = 5s 2 4d 9        but    Ag +  = 4d 10 , Ag 2+  = 4d 9 , etc Similarly:  Cd 2+  = 4d 10      Ir 3+  = 5d 6       Mn 4+  = 3d 3       etc Rh 2+  =                W 3+  =              Cu 2+  =           Zr 2+     Co 3+  = 1
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General properties of TM’s .    1. all are  metals 2. all are  solids  at 298  K, except  mercury  (Hg) 3. all are  stable  in multiple  oxidation  states  except  groups  3 and  12 4. redox  reactions  are  com m on 5. partially-filled  d-shell  gives  colored  species 6. partially-filled  d-shell  often  results  in unpaired  electrons. 7. size  of M n+  ions down a group:  3d < 4d   5d (due to an effect called the lanthanide  contraction). 8. size of M n+  across a period (L-to-R): decreases at first, then remains fairly constant. 9. electronegativity down a group: 3d > 4d < 5d  10.electronegativity across a period: increases across a period, but not much. 11. Ionization energies across a period: increase strongly L-to-R.  1 st Transition Series (“the 3d metals”) Most  important  property  is multiple  oxidation  states.   maximum  oxidation  state  = loss  of all outer  electrons,  but  not  always  possible  (too  difficult)   (see  Figure  22.4) ■ = most common oxidation states ● = less common or rare oxidation states 2
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Trends in Bonding : higher  oxidation  states  give  more  covalent  bonding  (to  reduce  hi   charge- to-size  ratio  i.e.  high  charge  density).   Thus,      TiCl 4  is a colorless, covalent liquid (like CCl 4 )      TiCl 2  is a white ionic solid     (like CaCl 2 This is the same trend as in the main groups (PbCl
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Chapter 22 Transition Metals Week 1 2009 - CHAPTER 23 TM =...

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