Classification of Blocks

Division of Elements into S, p, d & f blocks and their Electronic Configurations:

Elements in the periodic table have been divided into four blocks. This division is based upon the electronic configuration of the element. These are

(i) S-block elements:

Elements in which the last electron enter in the S-orbital of their respective outermost shells are called S-block elements. Since S-subshell contains only two electrons, so their are only 2 groups of S-block, first group is called alkali Metal (ns¹) and second group is called alkaline earth metal (ns²). The general electronic configuration of S-block element are ns^1-2 where n = 2-7

General characteristics of S-block Elements:

1. They are soft metals with low melting and boiling points.

2. They have low Ionization energy and highly Electropositive.

3. They are very reactive metals.

4. They are strong reducing agents.

5. All are good conductors of heat and electricity.

(ii) p-block Elements:

Elements in which the last electron enters in anyone of the three p-orbitals of their respective outermost shells are called p-block elements. p-orbital can accommodate six electrons , So there are total six groups in the p-block.The group 13 is called Boron family (ns² np¹), the group 14 is called carbon family (ns² np²), the group 15 is called nitrogen family (ns² np³), the group 16 is called oxygen family or chalcogens (ns²np⁴), the group 17 is called halogens (ns²np⁵) and last group is called Inert gases (ns²np⁶). The general electronic configuration of p-block elements is ns²np^1-6 where n=2-6

(a) The elements of S & p-block are collectively called representative.

General characteristics :

1. Their Ionization energies are comparatively higher than S-block elements.

2. They mostly form covalent compounds.

3. Some of them show more than one oxidation state.

4. They include both metal and non-metals. Non metals are much higher than metals. Metallic characteristics increase down the group.

(iii) d-block elements:

Elements in which the last electron enters in any one of the five d-orbitals of their respective penultimate shells are called d-block elements. d-orbital can accommodate 10 electrons, so there are total 10 groups in the d-block. These are from 3-12 in the periodic table. They are further divided into four series, called as first transition series, second , third and four transition series . General Electronic configuration of d-block is (n-1)d^1-10 ns^0-2

General characteristics :

1. They are hard, malleable and ductile with high melting and boiling points.

2. They are good conductors of heat and electricity.

3. They show variable oxidation states.

4. They form coloured complexes.

5. They form both ionic and covalent compounds.

6. Most of transition metals form alloys.

(vi) f-block Elements:

Elements in which the last electron enters in any one of the seven f-orbitals of their respective anti penultimate shells are called f-block elements. General outermost shell electronic configuration of f-block element is        (n-2) f^0-14(n-1)d^0-2 ns² where n=6-7

They are also called as inner transition elements.

General characteristics:

1. They are heavy metals.

2. They are generally high melting and boiling points.

3. They show variable oxidation states.

4. Their compounds are generally coloured.

5. They have high tendency to form complexes.

6. Most of elements of the actinoid series are radioactive.