Quantum Numbers in Chemistry

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Quantum Numbers in Chemistry

The set of four numbers which give complete information about the electron in an atom i.e., energy, orbital occupied, size, shape and orientation of that orbital and the direction of electron spin.

(a) Principal Quantum Number (n)

It gives the major energy level to which the electron belongs.

Thus, n = 1, 2, 3,… etc depending upon whether the electron belongs to first, second, third etc. energy levels For the first energy level (K – shell) n = 1, for second (M – shell) n = 2, etc.

(b) Azimuthal (or) Subsidiary (or) Angular Momentum Quantum Number (I)

It gives the energy level of subshells. It gives the following information :

• Number of subshells present within a main shell.
• Shapes of subshells.
• Contribution of energy due to angular momentum towards the total energy of the electron.

• For a given value of n, l can have values from 0 to (n – 1).
• For n = 1(K), l = 0 i.e. one subshell (s)
• n = 2 (L), I = 0, 1 i.e., two subshells (s, p)
• n = 3 (M), l = 0, 1, 2 i.e., three subshells (s, p, d)
• n = 4 (N), I = 0, 1, 2, 3 i.e., four subshells (s, p, d, f)

Order of energies : s < p < d < f
It was proposed by Sommerfeld.

(c) Magnetic Quantum Number (m)

It tells the number of orditals present within the same subshell.

For a given value of I, m can have values from -l to +l including 0, making a total of (2l + 1) values.

These quantum number also give the orientation of the orbital.
The number of orbital in a shell with principal quantum number n is equal to n²
The orbitals having same energy level are called degenerate orbitals.

S. No.	Commands	Headquarters
1	Western Command	Chandigarh
2	Eastern Command	Kolkata
3	Northern Command	56 A.P.O
4	Southern Command	Pune
5	Central Command	Lucknow
6	Army Training Command	Shimla
7	South Western Command	Jaipur

It was given by Lande to explain Zeeman and Stark effects.

(d) Spin Quantum Number (s)

This arises due to the spinning of the electron about its own axis.

It can be clockwise represented by +1 / 2 or or anticlockwise represented by -1/2.

This is the only quantum number that has non – integral values. It was introduced by Uhlenbeck and Goudsmet.

Distribution of Electrons in Quantum Levels :

S No	Place	City/State
1	Ajanta	Aurangabad
2	Akbar's Tomb	Sikandara
3	Ambernath Cave	Kashmir
4	Amber Palace	Jaipur
5	Anand Bhavan	Allahabad
6	Bhakra Dam	Punjab
7	Birla Planetarium	Kolkata
8	Black Pagoda	Konark (Orissa)
9	Bodhisattva	Ajanta Caves
10	Brihadeeswara Temple	Tanjore
11	Brindavan Gardens	Mysore (Karnataka)
12	Buland Darwaza	Fatepur Sikri
13	Charminar	Hyderabad
14	Chenna Kesava Temple	Belur
15	Chilka Lame	Near Bhubaneswar
16	Dal Lake	Srinagar
17	Dilwara Temples	Mt. Abu
18	Elephanta Caves	Mumbai
19	Golden Temple	Amirtsar
20	Gol Gumbaz	Bijapur
21	Hanging Gardens	Mumbai
22	Hawa Mahal (Palace of Winds)	Jaipur
23	Howrah Bridge	Kolkata
24	Island Palace	Udaipur
25	Itmad-ud-Daulah's Tomb	Agra
26	Jagannath Temple	Puri
27	Jama Masjid	Delhi
28	Jantar Mantar	Delhi
29	Jog (Geresoppa) Falls	Mysore
30	Kailasanath Temples	Ellora
31	Kanyakumari Temples	Cape Comorin
32	Khajuraho	Bhopal
33	Konark	Puri
34	Lal Bagh Gardens	Bangalore
35	Mahakaleeswar Temple	Ujjain
36	Mahesuramurthi (Trimurti)	Elephanta Caves
37	Malabar Hills	Mumbai
38	Manmandir Palace	Gwalior Fort
39	Marble Rocks	Jabalpur
40	Marina Beach	Chennai
41	Meenakshi Temple	Madurai
42	Padmanabha Temple	Trivandrum
43	Panch Mahal	Fatepur Sikri
44	Tower of Fame	Chittorgarh