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A transition element may be defined as an element whose atom in the ground state or ion in common oxidation state has incomplete sub-shell, has electron 1 to 9. It is called transition element due to fact that it is lying between most electropositive (s-block) and most electronegative (p-block) elements and represent a transition from them. The general electronic configuration of these element is (n–1)1 to 10 ns 0 to 2
The definition of transition metal excludes Zn, Cd and Hg because they have complete d- orbital. Their common oxidation state is Zn++, Cd++, Hg++ They also do not show the characteristics of transition element. Element of group 3 (Sc, Y, La and Ac) and group 12 (Zn, Cd, Hg) are called non typical transition element.
First transition or 3d series :
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Scandium |
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3d-orbitals are filled up |
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Second transition or 4d-series :
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Yttrium |
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4d-orbitals are filled up |
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Third transition or 5d-series :
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5d-orbitals are filled up |
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[Xe] 4f145d26s2 |
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Fourth transition or 6d-series :
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Electronic configuration |
Actinium |
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6d-orbitals are filled up |
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Elements marked with asterisk have anomalous configurations. These are attributed to factors like nuclear-electron and electron-electron forces and stability of half filled and full filled orbital.
All transition elements are d block elements but all d block elements are not transition elements.
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