Name: Dr. Pramod B. Thakur Class: S. Y. B Name: Dr. Pramod B. Thakur Class: S.Y.B.Sc Subject: Inorganic Chemistry Title of Topic: Comparative Chemistry of Transition Metals

SYBSC-Paper-II, Unit-II Paper Code-USCH302 Comparative Chemistry of Transition Metals Teacher: Dr. Pramod B. Thakur

Difference between the properties of elements of 3d series and 4d, 5d series Ambiguous Electronic configuration Ability to form cluster compounds Stability of oxidation state Geometry of Co-ordination compound Atomic and Ionic size Magnetic properties

Main (Representative), Transition metals, lanthanides and actinides (rare earth)

1. Ambiguous Electronic configuration 3d series Sc (Z = 21), [Ar] 3d1 4s2 Ti (Z = 22), [Ar] 3d2 4s2 V (Z = 23), [Ar] 3d3 4s2 Cr (Z = 24), [Ar] 3d5 4s1 Mn (Z = 25), [Ar] 3d54s2 Fe (Z = 26), [Ar] 3d6 4s2 Co (Z = 27), [Ar] 3d7 4s2 Ni (Z = 28), [Ar] 3d8 4s2 Cu (Z = 29), [Ar 3d10 4s1 Zn (Z = 30), [Ar] 3d10 4s2 [Ar] = 18

4d series Electronic configuration [Kr] = 36 Element Symbol At.No. Electronic configuration Yttrium Y 39 [Kr] 4d15s2 Zirconium Zr 40 [Kr] 4d25s2 Niobium Nb* 41 [Kr] 4d45s1 Molybdenum  Mo*  42 [Kr] 4d55s1 Technetium Tc 43 [Kr] 4d55s2 Ruthenium Ru* 44 [Kr] 4d75s1 Rhodium Rh* 45 [Kr] 4d85s1 Palladium Pd* 46 [Kr] 4d105s0 Silver Ag* 47 [Kr] 4d105s1 Cadmium Cd 48 [Kr] 4d105s2 [Kr] = 36

5d series Electronic configuration [Xe] = 54 Element  Symbol           At. No.   Electronic configuration Lanthanum La 57 [Xe] 5d16s2 Hafnium Hf 72 [Xe] 4f145d26s2 Tantalum T a 73 [Xe] 4f145d36s2 Tungsten W 74 [Xe] 4f145d46s2 Rhenium Re 75 [Xe] 4f145d56s2 Osmium Os 76 [Xe] 4f145d66s2 Iridium Ir 77 [Xe] 4f145d76s2 Platinum Pt* 78 [Xe] 4f145d106s0 Gold Au* 79 [Xe] 4f145d106s1 Mercury Hg 80 [Xe] 4f145d106s2 [Xe] = 54

2. Ability to form cluster compounds Complex involving Metal-Metal bonds are called as metal clusters Elements of second and third series have greater tendency to form cluster compounds than elements of first transition series. Eg: Chloride and carbonyls cluster compounds. 3d Series 4d series 5d series

3. Stability of Oxidation state In first series, lower +2, +3 oxidation state are stable and higher oxidation state are unstable. In second and third series, lower +2, +3 oxidation state are unstable and higher oxidation state are stable. Eg: Co+2 is stable, but Rh+2, Ir+2 are not stable, Re+7, Tc+7, are stable but Mn+7 is not stable 3d Series 4d series 5d series

4. Geometry of Co-ordination Complexes In second and third series elements forms co-ordination compounds with higher co-ordination number 7 & 8. In First series elements do not forms co-ordination compounds with higher co-ordination number. 3d Series 4d series 5d series

5. Atomic and Ionic Size Ionic radii of First series elements are less than second series elements which is less than third series elements. But there is very small difference in ionic radii of second series elements and third series elements. Eg: Co+3 = 0.63Ǻ, Rh+3 = 0.81 Ǻ, Ir+3 = 0.82 Ǻ Due to similarities in ionic radii of second series elements and third series elements, they have very similar properties and hence they are known as “Chemical Twin” 3d Series 4d series 5d series

Atomic Radius

6. Magnetism Magnetic moments of First series elements are calculated only by considering spin motion. Magnetic moments of Second series elements and Third series elements are calculated by considering both spin motion and orbital motion. 3d Series 4d series 5d series