s block and p block elements

Classification of periodic table:

           On the basis of subshell electronic configuration, elements in the periodic tables are classified into 4 blocks 

 I.e. s block,  p block  , d block and  f block.

S block :

Element in which the last electron enters into the s-sushell of the outermost shell are called s-block elements.

   S block consists of elements in the first and second group  and He.

Group number & period number

Number of electrons in the  last s subshell determines  the group number.

[The superscript number in the outermost s subshell indicate the group number]

Period number =number of shell 

I.e. period number is the shell number of the outermost shell. 

Eg : 1. K(19)

              Electronic configuration: 1s22s22p63s2            3p64s1 

          Block : s block  

           Group: 1

            Period  :4

2. Mg(12)

              

Electronic configuration: 1s22s22p63s2            

          Block : s block  

           Group: 2

            Period  :3

P block :

  The  elements in which last electrons enters the  p  orbital of their valence shell are called p block elements. It consist of  group 13 to 18 except helium.

[To find the group number of  p  block elements add 12 to the electrons in the outermost p subshell.Period number  is same as the shell number. ]

Examples:

1.Si(14)

              Electronic configuration: 1s22s22p63s2            3p2

          Block : p block  

           Group: 12+2=14

            Period  :3

2.Ga(31)

   

 Electronic configuration: 1s22s22p63s2 3p6 4s2   3d104p1

  Block : p block  

           Group: 12+1=13

            Period  :4

3.Ar(18)

              

Electronic configuration: 1s22s22p63s2  3p6

          Block : p block  

           Group: 12+6=18

            Period  :3

Workout problems:

The outermost electronic configuration of element X is  3s2   and the element Y is 3s2   3p5 .Find the following 

(1) Complete the electronic configuration 

(2) Atomic number 

(3) Period 

(4) Group 

(5) Valency

(6) Oxidation state 

(7) Block

Answer :

  

Element X :

    (1) 1s22s22p63s2 

  

   (2)Atomic number :12

(3) Period :3

(4) Group :2

(5) Valency : 2

(6) Oxidation state :+2

(7) Block :  s block 

 

Element Y:

    (1) 1s22s22p63s2  3p5

  

   (2)Atomic number :17

(3) Period :3

(4) Group :12+5=17

(5) Valency : 1

(6) Oxidation state :-1

(7) Block :  p block 

Activity :

The outermost electronic configuration of element A is   3s1and the element B is 4s24p4  .Find the following 

(1) Complete the electronic configuration 

(2) Atomic number 

(3) Period 

(4) Group 

(5) Valency

(6) Oxidation state 

(7) Block