chemistry

CLASSIFICATION OF ELEMENTS INTO 4 BLOCKS

The elements are classified into four blocks as s-block, p-block, d-block and f-block based on the orbital into which differentiating electron enters.

This classification is based on electronic configuration.

s-block contains 2 groups, p-block contains 6 groups, d-block contains 10 groups and f-block contains 14 groups.

s-block is at the extreme left and p-block is at the extreme right of the periodic table. d-block is kept in between s-block and p-block.

f-block is separately placed below the main body of the table.

s-block :

Differentiating electron enters into s-orbitals of valence shell.

It consists of I -A and II - A groups namely alkali and alkaline earth metals. They are

1)  Most reactive metals.

2)  Most electropositive metals.

3)      Strongly reducing in nature.

4)      Strong tendency to lose electrons.

The S-block element placed in P-block is He. They exhibit only positive oxidation states. p-block:

Differentiating electron enters into p-orbitals of valence shell. It consists of III-A to VII-A and '0' group.

Electronic configuration is ns² np¹to ns² np⁵and ns² np⁶.

It consists of all types of elements i.e. metals, non-metals, metalloids. These are more electronegative than s-block elements.

Most electronegative elements are present in this block. They are also reactive elements except 'O' group.

They exhibit positive and negative oxidation states.

d – block :

Differentiating electron enters into d-orbitals of (n – 1) shell. It consists of all groups – B and VIII group. (total ten groups)

Electronic configuration: ns², (n – 1 )d^1–10 All d-block elements are metals.

These are placed in 4^th, 5^th, 6^thand 7^th periods. They are hard metals with high M.P.'s and B.P's. f – block :

Differentiating electron enters into f-orbitals of (n–2) shell. Electronic configuration: ns², (n–1)d^{(0 or 1)}, (n–2)f^1-14.

They are present in two horizontal rows at the bottom of periodic table namely lanthanides and actinides.

They belong to 6^th and 7^th periods. They belong to III-B group.

Many of them are artificially prepared and do not occur in nature. They are all metals.