Division of Periodic Table into Blocks

• The long form of periodic table can be divided into four main blocks.
• These four main blocks are s, p, d and f –blocks.
• The division of elements into blocks is purely based upon the electronic configuration.
• The nature of the subshell in which the last electron of that atom enters, determines the block to which that element belongs.

A) s-Block elements

• s-block elements are those elements in which the last electron enters the s-subshell of their outermost energy level.
• This block is situated at extreme left of the periodic table.
• It contains elements of group 1(IA) and 2(IIA).
• Their general configuration is ns^1-2, where n represents the outermost orbit or shell.
• The elements of group IA are called alkali metals whereas IIA elements are called alkaline earth metals.

Characteristics

1. They are soft metals.
2. They are highly electropositive in nature.
3. They have low ionization energies.
4. They are very reactive and form ionic compounds.
5. They show oxidation state of +1 and +2.
6. They are good reducing agents.

B) p-Block elements

• p-block elements are those elements in which the last electron enters the p-subshell of their outermost energy level.
• The exception is helium (1s²).
• The general configuration of their outermost shell is ns²np^1-6.
• This block is situated at the extreme right of the periodic table and contains elements of group 13(IIIA), 14(IVA), 15(VA), 16(VIA), 17(VIIA) and 18(zero) of the periodic table.
• Most of these elements are non-metals, some are metalloids and a few heavy elements exhibit metallic character.

Characteristics

1. They are generally non-metals.
2. They are mostly highly electronegative in nature.
3. They form ionic as well as covalent compounds.
4. They generally form acidic oxides.
5. They show variable oxidation states.

C) d-Block elements

• Those elements in which the last electron enters the d-subshell of the outermost energy level are called d-block elements.
• Their general valance shell configuration is (n-1)d^1-10, ns^1-2, where n represents the outermost energy level.
• The first three transition series are first, second and third transition series and they involve filling of 3d, 4d and 5d orbitals respectively.

Characteristics

1. They are hard, high melting metals.
2. They form ionic as well as covalent compounds.
3. Most of them exhibit para-magnetism.
4. They form coloured complexes.
5. They show variable valency and oxidation states.
6. Most of them possess catalytic properties.

E) f-block elements

• Those elements in which the last electron enters the f-subshell of the ante-penultimate (third to the outermost orbit) shell are called f-block elements.
• Their general configuration is (n-2)f^1-14, (n-1)d^0-5, ns² where n represents the outermost shell or orbit.
• They consist of two series of elements placed at the bottom of the periodic table.
• The first series follows lanthanum (₅₇La) and are called lanthanides.
• The second series follows actinium (₈₉Ac) and are called actinides.

Characteristics

1. They are high melting metals.
2. They have high densities.
3. They form coloured compounds.
4. They show variable oxidation states.
5. Most of the elements of actinide series are radioactive.

Image source: thoughtco

Points to Know

• The elements of s-block and p-block are called representative elements.
• The elements of d-block are called d-transition elements. The name is derived from the fact that they represent transition, i.e., change in character from reactive metals (elements of group IA and IIA) on one side to non-metals on the other side.
• The elements of f-block are called f-transition or inner transition elements.

References:

i) https://chemistry-desk.blogspot.com/2011/06/division-of-periodic-table.html

ii) https://examplespedia.com/classification-of-elements/

iii) https://www.sarthaks.com/598355/explain-classification-of-elements-into-different-blocks-in-the-periodic-table

Division of Periodic Table into Blocks