1. 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

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

3. 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

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

5. 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

6. 4d series Electronic configuration [Kr] = 36
Element Symbol At.No. Electronic configuration
Yttrium Y [Kr] 4d15s2
Zirconium Zr [Kr] 4d25s2
Niobium Nb* [Kr] 4d45s1
Molybdenum  Mo*  [Kr] 4d55s1
Technetium Tc [Kr] 4d55s2
Ruthenium Ru* [Kr] 4d75s1
Rhodium Rh* [Kr] 4d85s1
Palladium Pd* [Kr] 4d105s0
Silver Ag* [Kr] 4d105s1
Cadmium Cd [Kr] 4d105s2
[Kr] = 36

7. 5d series Electronic configuration [Xe] = 54
Element  Symbol           At. No.   Electronic configuration
Lanthanum La [Xe] 5d16s2
Hafnium Hf [Xe] 4f145d26s2
Tantalum T a [Xe] 4f145d36s2
Tungsten W [Xe] 4f145d46s2
Rhenium Re [Xe] 4f145d56s2
Osmium Os [Xe] 4f145d66s2
Iridium Ir [Xe] 4f145d76s2
Platinum Pt* [Xe] 4f145d106s0
Gold Au* [Xe] 4f145d106s1
Mercury Hg [Xe] 4f145d106s2
[Xe] = 54

8. 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

9. 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

10. 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

11. 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

12. Atomic Radius

13. 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