How to find electronic configuration of atoms? Give the full study materials.

To find electronic configuration of atoms, you should know its atomic numbers.

 

For electronic configuration of elements, the most important thing that you should be aware of -

The order in which orbitals of different subshells are filled. We know that this order is determined by the (n + l) rule and is as follows:

 

Order for filling subshells: 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p 

where the number indicates the energy level and the letter indicates the subshell being filled.

Maximum number of electrons in each subshell: s=2, p=6, d=10, f=14 

A superscipt number after the letter of the subshell shows how many electrons occupy that subshell.

The helium atom has 2 electrons, both in the s subshell of the first energy level. 
Its sub-shell electron configuration is 1s²

The neon atom has 10 electrons. 
2 electrons in the s subshell of the first energy level: 1s² 
8 electrons in second energy level, made up of 2 electrons in an s subshell and 6 electrons in a p subshell: 2s² 2p⁶ 
Its subshell electron configuration is 1s² 2s² 2p⁶

The argon atom has 18 electrons. 
2 electrons in the s sub-shell of the first energy level: 1s² 
8 electrons in the second energy level made up of 2 electrons in an s subshell and 6 electrons in a p subshell: 2s² 2p⁶ 
8 electrons in the third energy level made up of 2 electrons in an s subshell and 6 electrons in a p subshell: 3s² 3p⁶ 
Its subshell electron configuration is: 1s² 2s² 2p⁶ 3s² 3p⁶

Table showing examples of electronic configuration of atoms and ions are as follows:

Atom	Z	No. Electrons = Z	Subshell Electron Configuration	Ion	No. Electrons = Z - charge	Subshell Electron Configuration
H	1	1	1s1	H-	1 - (-1) = 2	1s2
He	2	2	1s2
Li	3	3	1s2 2s1	Li+	3 - 1 = 2	1s2
Be	4	4	1s2 2s2	Be2+	4 - 2 = 2	1s2
B	5	5	1s2 2s2 2p1	B3+	5 - 3 = 2	1s2
C	6	6	1s2 2s2 2p2	C4+	6 - 4 = 2	1s2
N	7	7	1s2 2s2 2p3	N3-	7 - (-3) = 10	1s2 2s2 2p6
O	8	8	1s2 2s2 2p4	O2-	8 - (-2) = 10	1s2 2s2 2p6
F	9	9	1s2 2s2 2p5	F-	9 - (-1) = 10	1s2 2s2 2p6