Question

On what basis have elements classified into blocks S, P, D and F?

Answer 1

On the basis of valence shell electronic configuration, the periodic table is divided into four distinct blocks of elements.
* All the elements in which the last electron enters "ns" orbital are known as s-block elements.Elements of group I-A and II-A belong to s-block.
* The elements in which valence electrons enter p-orbital and this orbital is progressively filled are called p-block elements. P-block consists of the elements of group III-A to VII-A (zero-group).
* The elements in which last electron enters (n-1) d-orbital are called d-block elements or outer transition elements.
* The elements in which last electron enters (n-2) f-orbital are called f-block elements or inner transition elements.