Comparative Study of d block elements,

It is the ppt that describes the properties of d block elements,and comparision of 3d,4d,5d elements of d block elements

1. KUVEMPU UNIVERSITY Department of P.G. Studies and Research in Chemistry Jnana Sahyadri, Shankaraghatta – 577 451 A SEMINAR ON COMPARATIVE STUDY OF 3d,4d AND 5d ELEMENTS PRESENTED BY ARUN CHIKKODI. M.Sc., II semester Department of Chemistry. Jnana Sahyadri, Shankaraghatta

2. CONTENTS Introduction. Comparative study of 3d 4d and 5d elements . Ionic radius Oxidation state Magnetic properties Metal metal bonding Coordination number of complexes Abundance conclusion

3. INTRODUCTION The elements which have partly filled d subshell are called d block elements. They are also called transition elements as their properties are partly of s-block and partly of p-block elements These d block elements include three complete series I,e.,3d,4d,&5d., whereas one incomplete series 6d. The 4d and 5d transition series elements have similar characteristics , but show typical differences from 3d series.

4. Sc Ti V Cr Mn Fe Co Ni Cu Zn Y Zr Nb Mo Tc Ru Rh Pd Ag Cd La Hf Ta W Re Os Ir Pt Au Hg 3d series 4d series 5d series d- block elements

5. COMPARATIVE STUDY OF 3d,4d AND 5d ELEMENTS

6. IONIC RADIUS On moving down a group in a periodic table ,the ionic radii of the elements increases. The 4d elements are larger in size as compared to the 3d elements. Because of increase in the number of electrons and higher principal quantum numbers of elements. There is very little differences in ionic radii of the elements of 4d and 5d series due to lanthanide contraction.

7. OXIDATION STATE The 4d and 5d elements exist higher oxidation states than 3d elements because they have low ionization energy. Higher oxidation state is generally more stable. Example: RuO 4 , WCl 6 , PtF 6 are stable. [MoO 4 ] 2- and [WO 4 ] 2- are highly stable and are not easily reduced. Where as [CrO 4 ] 2- is a very strong oxidising agent and is easily reduced.

8. MAGNETIC PROPERTIES According to Crystal field theory ,d orbitals in complexes splits into t 2g and e g sublevels. The magnitude of splitting for any given ligand is greater for 4d and 5d members than 3d elements. So these metals form predominantly spin paired complexes. Even the weaker ligand the complexes are diamagnetic in nature. The 3d elements form spin – free, paramagnetic complexes with weak ligands.

9. METAL-METAL BONDING The 4d and 5d elements have a greater tendency to form metal-metal bonds compare to 3d elements. As a result a large number of polynuclear and cluster compounds are known. Examples : [Re 2 Cl 8 ] 2- , [Mo 2 Cl 9 ] 3- , [Rh 4 (CO) 12 ] and [Ir 4 (CO) 12 ].

10. COORDINATION NUMBER OF COMPLEXES For the 3d series metals , complexes with co –ordination number 6 are most common. The 4d and 5d elements are larger in size and can accommodate a larger number of ligands around them. Therefore the 4d and 5d elements form complexes with co-ordination number greater than 6. Examples: [Na 3 (ZrF 7 )] and [Cu 2 (ZrF 8 )].

11. ABUNDANCE The 3d series transition metals are more abundant in the earth’s crust as compared to the heavier elements. The first series constitute about 6.8% of the earth’s crust. The second and third series constitute only 0.025% of the earth’s crust. The element technetium does not exits in nature.

12. CONCLUSION The 4d elements are larger in size as compared to 3d elements. The 4d and 5d elements exists higher oxidation state than 3d elements. The 3d elements forms paramagnetic complexes whereas 4d and 5d elements forms diamagnetic complexes.

13. REFERENCES Principles of Inorganic Chemistry , B.R. Puri, L.R. Sharma, K.C. Kalia, Milestone Publishers, New Delhi, India, 2008. Page number- 716-718 Concise Inorganic Chemistry, 5 th Edition, J.D. Lee, Blackwell Science Ltd., London, 2003. Page number- 674-676 Internet source