ELECTRONIC CONFIGURATION 2( Block, Period ,Group)

This is the 2^nd part of ELECTRONIC CONFIGURATION

If you have not read the 1^st part then

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In the 2^nd part we will learn about application or use of electronic configuration. Here we will see how can we know element‘s atomic number, its block and the group and period of that element from the electronic configuration .

What is Group in periodic table?

The vertical columns in the periodic table are called group. There are 18 groups in periodic table.

First two groups are known as S BLOCK.

Next ten groups are known as D BLOCK.

Last six groups are known as P BLOCK.

There are actinides and lanthanides series are below the periodic table are known as f BLOCK.

What is Period in periodic table?

The horizontal rows in the periodic table are called period. There are 7 period in periodic table.

First three periods are known as Short Period.

Next two periods are known as Long Period.

Last two periods are known as Longest Period.

See the periodic table.

 >>>Click here to see image of period table

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Let’s take an example of electronic configuration of an element.

How to know atomic number and elements name?

Add the electron to know the atonic number. Because in ground state number of electron is equal to number of proton is equal to atomic number .

By knowing atomic number we can say elements name.

For example:

1s² 2s² 2p⁶ 3s²  3p⁶   4s² 

2+2+6+2+6+2=20

It has 20 electron .so its atomic number is 20.

That means,  it is calcium.

How to know in which periods the element is situated?

See the highest number of shell in the electronic configuration.

For example:

1s² 2s² 2p⁶ 3s²  3p⁶   4s² 

Here, highest number of shell is 4, so this element is situated in 4^th period.

How to know in which block the element is situated?

See the last set of electronic configuration.

See the block name with highest shell number having high subshell  for recognizing S and P block.(see ex-1 and 3) in ex 3 we have 3s²  3p⁵  but we will choose shell number having high subshell  i.e. 3p⁵.

If an element has configuration like this in the last.  ns^1-2  (n-1)d^1-10 then the elements belongs to D block (see ex-2)

For example:

    1)    1s² 2s² 2p⁶ 3s²  3p⁶   4s²   ; Here , this element is in S BLOCK.

    2)    Ar   4s²  3d⁶  ; this element is in D BLOCK.

    3)    1s² 2s² 2p⁶ 3s²  3p⁵  ; this element is in P BLOCK.

Let’s understand the general electronic configuration of S BLOCK , P BLOCK , D BLOCK and F BLOCK. We can say block name by understanding this.

n = no of shell (present at last in electronic configuration.)

General electronic configuration of 

S BLOCK  =  ns^1-2

Na	1s2 2s2 2p6 3s1

Mg	1s2 2s2 2p6 3s2

General electronic configuration of

P BLOCK  =  ns²   np^1-6

Al	1s2 2s2 2p6 3s2  3p1
Si	1s2 2s2 2p6 3s2  3p2
P	1s2 2s2 2p6 3s2  3p3
S	1s2 2s2 2p6 3s2  3p4
Cl	1s2 2s2 2p6 3s2  3p5
Ar	1s2 2s2 2p6 3s2  3p6

General electronic configuration of 

D BLOCK  =  ns^1-2  (n-1)d^1-10 

Sc	Ar   4s2  3d1
Ti	Ar   4s2 3d2
V	Ar   4s2  3d3
Cr	Ar   4s1  3d5
Mn	Ar   4s2  3d5
Fe	Ar   4s2  3d6
Co	Ar   4s2  3d7
Ni	Ar   4s2  3d8
Cu	Ar   4s1  3d10
Zn	Ar   4s2  3d10

General electronic configuration of

F BLOCK  =  (n-1)f^1-14  (n-1)d^0-10  ns^1-2

72	Hf	Xe  4f14  5d2 6s2
73	Ta	Xe  4f14  5d3 6s2
74	W	Xe  4f14  5d4 6s2
75	Re	Xe  4f14  5d5 6s2

How to know in which group the element is situated?

Identifying group 1-2 (s block)

If the element belongs to s block ,see the electron of that set. The number of electron will be group number.

For example

    1)    1s² 2s² 2p⁶ 3s¹  (Sodium)

 3s¹   has one electron so it is in group no1.

    2)    1s² 2s² 2p⁶ 3s²  3p⁶   4s²  (Calcium)

4s²  has two electrons so it is in group 2.

Identifying group 13-18 (p block)

First  see ,if the element belongs to p block ,then See the electron of that set(ns²   np^1-6 ). Then add 10 with the number of electron to find group number.

For example

    1)       1s² 2s² 2p⁶ 3s²  3p² (Silicon)

3s²  3p²    has 4 electron so it is in group no (10+4)=14.

    2)      Ar    3d¹⁰   4s²  4p⁵ (Bromine)

4s²  4p⁵    has 7 electron so it is in group no (10+7)=17.

Identifying group 3-12 (d block)

First  see ,If the element belongs to D block ,then See the electron of that set( ns^1-2  (n-1)d^1-10  ). Then the sum of number of electron will be group number.

For example

    1)       Ar   4s²  3d⁵ (manganese)

4s²  3d⁵   has 7 electron so it is in group no 7.

    2)        Xe  4f¹⁴  5d⁴ 6s² (Tungsten)

5d⁴ 6s²  has 6 electrons so it is in group no  6.