ELECTRONIC CONFIGURATION

Electronic configuration (E.C.) means configuring electron in an atom.

There are a lots of way from we can do e.c. Of an element. We can do it by shell wise, subshell or orbit wise or we can do it by orbital wise or spin wise.

Basically according to quantum theory, there are four quantum number. The quantum theory is nothing but it is a complete analysis of structure, shape, orientation, spin and magnetic property of an element. Here we only focus on our topic, so we only understand main point of quantum number but not in detail.

ELECTRONIC CONFIGURATION part 2 .
 >>>click hereIn 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 .

     1.   Principle quantum number – It is basically shell or energy level relating quantum number. This quantum number tells in which shell or energy level electron is present. It is denoted by n which means no of shell. A shell can contain 2n² no. Of electron in it.

For example:

Shell  ( n)	maximum electron
1 or k	2
2 or l	8
3 or m	18
4 or n	32

       2.  Azimuthal quantum number - – it is basically subshell relating quantum number.it tell about shape of orbitals or subshell. It is denoted by l (0, 1, 2, and 3).

Subshell	Azimuthal quantum number (l)
S	0
P	1
D	2
F	3

 the no. Of subshell in a shell can be determined by value of n and l. This l may have value from

0 to (n-1) for each of principle energy level.

N	L to (n-1)	Subshells	Subshells with n
1	0 to 0	S	1s
2	0 to 1	S,p	2s, 2p
3	0 to 2	S,p,d	3s, 3p, 3d
4	0 to 3	S,p,d,f	4s, 4p, 4d, 4f

      3.   Magnetic quantum numbers – it is related to orientation of subshell. These different orientations are called orbital. It is denoted by ml.

We can find no of orbital and electron present in a subshell with the help of l. These calculations can be done by (2l+1).

Subshell	No. Of orbitals (2l+1)	No. Of electron (2ml)
S	1	2
P	3 (px ,py, pz)	6
D	5 (dxy, dyz, dxz, dx2-y2, dz2 )	10
F	7	14

     4.        Spin quantum number- it tells about spins of electron in an orbital of an atom. It is denoted by ms.  The spin of electron is denoted by arrow sign (↑,↓) . One arrow denotes clockwise spin and other denotes anti- clock wise spin.

Now ,we understand the rules of configuration.

    1)   Bohr-bury scheme- This rule decide which orbital have more energy.

a.       If a subshell has lower value of (n+l) , that subshell having low energy.

Ex:- 4s=(4+0)=4 ,3d=(3+2)=5 ; here 3d has higher energy than 4s .

b.      If  value of (n+l) is same for two subshell then lower value of n has lower energy.

            ex;- 4s=(4+0)=4,3p=(3+1)=4; here 4s has higher energy than 3p.

    2)    Aufbau rule- According to this rule electrons are filled in a orbital on the basis of their respective energy. That means , electron having lower energy fills first in an orbital then electron having greater energy  fills.

1s<2s<2p<3s<3p<4s<3d<4p<5s<4d<5p<6s<4f<5d<6p<7s

   3)  Pauli exclusion principle- This principle states that no two electron in an atom can have same set of all four quantum number.

      4)  Hund’s rule- According to this rule in p, d ,f orbital ,the electrone will not pair up until all orbital not having atleast one electron.

       5)  Last shell of an atom can have maximum number of 8 electrons.

So, lets start e.c. of an atom

Ex:       mg ( magnesium)

Atomic number =12

Electronic configuration :    1s² 2s² 2p⁶ 3s²  (this is subshell wise configuration)

n	subshell	electron
1	1s2	2
2	2s2 2p6	8
3	3s2	2

Electronic configuration : 2,8,2  (this is shell wise configuration)

Electronic configuration:    1s² 2s² 2p_x²  2p_y²  2p_z² 3s²  (this is orbital wise configuration)

Electronic configuration: (this is spin wise configuration)↓↓↓↓↓↓

 # No of electrons present in shell(1,2,3,4)

n	n	subshell	Electrons in shell
1	K	1s	2
2	L	2s  2p	8
3	M	3s  3p  3d	18
4	N	4s  4p  4d  4f	32

IMPORTANT QUESTION FROM ELECTRONIC CONFIGURATION
EXCEPTION:
24- CHROMIUM and 29-COPPER has unique e.c..

A half filled and full filled orbital is more stable than less than half filled or less than full filled orbital. 

So, 24-Cr and 29-Cu want to achieve half filled and full filled D orbital respectively. so 24-Cr and 29-Cu complete its  half filled and full filled D orbital by borrowing a electron from 4s orbital.

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Click here to see image of period table

ELECTRONIC CONFIGURATION
z	symbol	Electronic configuration  ( subshell wise)	n (SHELL WISE)
			1	2	3	4	5	6	7
1	H	1s1	1
2	He	1s2	2
3	Li	1s2 2s1	2	1
4	Be	1s2 2s2	2	2
5	B	1s2 2s2 2p1	2	3
6	C	1s2 2s2 2p2	2	4
7	N	1s2 2s2 2p3	2	5
8	O	1s2 2s2 2p4	2	6
9	Fe	1s2 2s2 2p5	2	7
10	Ne	1s2 2s2 2p6	2	8
11	Na	1s2 2s2 2p6 3s1	2	8	1
12	Mg	1s2 2s2 2p6 3s2	2	8	2
13	Al	1s2 2s2 2p6 3s2  3p1	2	8	3
14	Si	1s2 2s2 2p6 3s2  3p2	2	8	4
15	P	1s2 2s2 2p6 3s2  3p3	2	8	5
16	S	1s2 2s2 2p6 3s2  3p4	2	8	6
17	Cl	1s2 2s2 2p6 3s2  3p5	2	8	7
18	Ar	1s2 2s2 2p6 3s2  3p6	2	8	8
19	K	1s2 2s2 2p6 3s2  3p6   4s1  or Ar   4s1	2	8	8	1
20	Ca	1s2 2s2 2p6 3s2  3p6   4s2  or Ar   4s2	2	8	8	2
21	Sc	Ar   4s2  3d1	2	8	9	2
22	Ti	Ar   4s2 3d2	2	8	10	2
23	V	Ar   4s2  3d3	2	8	11	2
24	Cr	Ar   4s1  3d5	2	8	13	1
25	Mn	Ar   4s2  3d5	2	8	13	2
26	Fe	Ar   4s2  3d6	2	8	14	2
27	Co	Ar   4s2  3d7	2	8	15	2
28	Ni	Ar   4s2  3d8	2	8	16	2
29	Cu	Ar   4s1  3d10	2	8	18	1
30	Zn	Ar   4s2  3d10	2	8	18	2
31	Ga	Ar   4s2  3d10  4p1	2	8	18	3
32	Ge	Ar   4s2  3d10  4p2	2	8	18	4
33	As	Ar   4s2  3d10  4p3	2	8	18	5
34	Se	Ar   4s2  3d10  4p4	2	8	18	6
35	Br	Ar   4s2  3d10  4p5	2	8	18	7
36	Kr	Ar   4s2  3d10  4p6	2	8	18	8
37	Rb	Kr  5s1	2	8	18	8	1
38	Sr	Kr   5s2	2	8	18	8	2
39	Y	Kr  4d1 5s2	2	8	18	9	2
40	Zr	Kr  4d2 5s2	2	8	18	10	2
41	Nb	Kr  4d4 5s1	2	8	18	12	1
42	Mo	Kr  4d5 5s1	2	8	18	13	1
43	Tc	Kr  4d5 5s2	2	8	18	13	2
44	Ru	Kr  4d7 5s1	2	8	18	15	1
45	Rh	Kr  4d8 5s1	2	8	18	16	1
46	Pd	Kr  4d10	2	8	18	18
47	Ag	Kr  4d10  5s1	2	8	18	18	1
48	Cd	Kr  4d10  5s2	2	8	18	18	2
49	In	Kr  4d10  5s2  5p1	2	8	18	18	3
50	Sn	Kr  4d10  5s2  5p2	2	8	18	18	4
51	Sb	Kr  4d10  5s2  5p3	2	8	18	18	5
52	Te	Kr  4d10  5s2  5p4	2	8	18	18	6
53	I	Kr  4d10  5s2  5p5	2	8	18	18	7
54	Xe	Kr  4d10  5s2  5p6	2	8	18	18	8
55	Cs	Xe  6s1	2	8	18	18	8	1
56	Ba	Xe  6s2	2	8	18	18	8	2
Lanthanide series (57-71)
57	La	Xe   6s2  5d1	2	8	18	18	9	2
58	Ce	Xe  4f2  6s2	2	8	18	20	8	2
59	Pr	Xe  4f3  6s2	2	8	18	21	8	2
60	Nd	Xe  4f4  6s2	2	8	18	22	8	2
61	Pm	Xe  4f5  6s2	2	8	18	23	8	2
62	Sm	Xe  4f6  6s2	2	8	18	24	8	2
63	Eu	Xe  4f7  6s2	2	8	18	25	8	2
64	Gd	Xe  4f7  5d1  6s2	2	8	18	25	9	2
65	Tb	Xe  4f9  6s2	2	8	18	27	8	2
66	Dy	Xe  4f10  6s2	2	8	18	28	8	2
67	Ho	Xe  4f11  6s2	2	8	18	29	8	2
68	Er	Xe  4f12  6s2	2	8	18	30	8	2
69	Tm	Xe  4f13  6s2	2	8	18	31	8	2
70	Yb	Xe  4f14  6s2	2	8	18	32	8	2
71	Lu	Xe  4f14  5d1  6s2	2	8	18	32	9	2
72	Hf	Xe  4f14  5d2 6s2	2	8	18	32	10	2
73	Ta	Xe  4f14  5d3 6s2	2	8	18	32	11	2
74	W	Xe  4f14  5d4 6s2	2	8	18	32	12	2
75	Re	Xe  4f14  5d5 6s2	2	8	18	32	13	2
76	Os	Xe  4f14  5d6 6s2	2	8	18	32	14	2
77	Ir	Xe  4f14  5d7 6s2	2	8	18	32	15	2
78	Pt	Xe  4f14  5d9     6s1	2	8	18	32	17	1
79	Au	Xe  4f14  5d10   6s1	2	8	18	32	18	1
80	Hg	Xe  4f14  5d10   6s2	2	8	18	32	18	2
81	Ti	Xe  4f14  5d10   6s2  6p1	2	8	18	32	18	3
82	Pb	Xe  4f14  5d10   6s2  6p2	2	8	18	32	18	4
83	Bi	Xe  4f14  5d10   6s2  6p3	2	8	18	32	18	5
84	Po	Xe  4f14  5d10   6s2  6p4	2	8	18	32	18	6
85	At	Xe  4f14  5d10   6s2  6p5	2	8	18	32	18	7
86	Rn	Xe  4f14  5d10   6s2  6p6	2	8	18	32	18	8
87	Fr	Rn  7s1	2	8	18	32	18	8	1
88	Ra	Rn  7s2	2	8	18	32	18	8	2
Actinides series (89-103)
89	Ac	Rn  6d1  7s2	2	8	18	32	18	9	2
90	Th	Rn  6d2  7s2	2	8	18	32	18	10	2
91	Pa	Rn  5f2  6d1  7s2	2	8	18	32	20	9	2
92	U	Rn  5f3  6d1  7s2	2	8	18	32	21	9	2
93	Np	Rn  5f4  6d1  7s2	2	8	18	32	22	9	2
94	Pu	Rn  5f6  7s2	2	8	18	32	24	8	2
95	Am	Rn  5f7  7s2	2	8	18	32	25	8	2
96	Cm	Rn  5f7  6d1  7s2	2	8	18	32	25	9	2
97	Bk	Rn  5f9  7s2	2	8	18	32	27	8	2
98	Cf	Rn  5f10  7s2	2	8	18	32	28	8	2
99	Es	Rn  5f11  7s2	2	8	18	32	29	8	2
100	Fm	Rn  5f12  7s2	2	8	18	32	30	8	2
101	Md	Rn  5f13  7s2	2	8	18	32	31	8	2
102	No	Rn  5f14  7s2	2	8	18	32	32	8	2
103	Lr	Rn  5f14  6d1  7s2	2	8	18	32	32	9	2
104	Rf	Rn  5f14  6d2  7s2	2	8	18	32	32	10	2
105	Db	Rn  5f14  6d3  7s2	2	8	18	32	32	11	2
106	Sg	Rn  5f14  6d4  7s2	2	8	18	32	32	12	2
107	Bh	Rn  5f14  6d5  7s2	2	8	18	32	32	13	2
108	hs	Rn  5f14  6d6  7s2	2	8	18	32	32	14	2

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