Question

what is d and f block element​

Answer 1

In transition elements the last electron enters penultimate d orbitals i.e. (n-1)d orbitals and that is why they are called d-block elements.The general valence shell configurations of transition elements is (n-1)d1–10.ns0, 1, 2. All the d-block elements are classified into four series viz 3d, 4d, 5d and 6d series corresponding to the filling of 3d, 4d, 5d and 6d orbitals.

f –block elements are also called inner transition elements. In these the last electron enters penultimate i.e. (n – 2)f f orbital. The differentiating electron in transition elements may enter either 4f or 5f orbitals based upon which they are differentiated into lanthanides and actinides.