Question

All d-block elements are not transition elements. Explain. 

OR 

Which of the d-block elements may not be regarded as the transition elements?

Answer 1

i. The d-block elements are those in which the last electron enters the d-orbital. 

ii. The transition elements are those elements which have incompletely filled (partly filled) d-subshells in their elementary state or in any one of their oxidation states. 

iii. Hence, only those d-block elements which have completely filled d-orbitals, (n-1)d¹⁰ are not transition elements. 

eg. Zn, Cd and Hg atoms have completely filled d-orbitals (3d¹⁰) in their ground state as well as in their oxidation states. Hence they are d-block elements, but not transition elements.