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1800-102-2727Let's say you are travelling from New Delhi to Visakhapatnam by train. You see that there is a 40-minute stop at Bhopal junction when you look at the train itinerary. Fortunately, you have an old buddy who lives in Bhopal who you haven't seen in a long time. You call him on the phone and invite him to come to see you at the train station.
How will your friend find you at the railway station?
You might believe that since you are acquainted, he won't have a hard time locating you. However, a railway station has 4-5 platforms and an average train has 24 carriages. Without knowing your train, coach, and seat number, he won't be able to locate you. So that your friend can quickly locate you, you provide a snapshot of your train ticket to avoid this issue.
Your ticket contains information such as the train number, departure time, coach number, and seat number. It also informs you of the likely location where finding you will be maximum.
Similarly, electrons can also be found in probable locations and these probable locations are denoted using quantum numbers.
On this concept page, we will get to know more about azimuthal quantum numbers in detail.
TABLE OF CONTENTS
An atom contains many orbitals. Thes orbitals are defined by a set of numbers called quantum numbers. To specify the shape, size and energy of the orbitals, three quantum numbers namely the principle quantum number (n), azimuthal quantum number (l) and magnetic quantum number (ml) are required. To specify the electron, an additional quantum number called spin quantum number (ms) is required. Thus each orbital in an atom is assigned three quantum numbers and each electron in an atom is assigned four quantum numbers.
1. Principal Quantum Number (n)
2. Azimuthal Quantum Number (l)
3. Magnetic Quantum Number (ml)
4. Spin electron Quantum Number (ms)
Principal quantum number determines the size and the energy of an orbital and is denoted by 'n'. Higher the value of n indicates a bigger size of the orbital.
Size of orbital ∝ n
Energy of the orbital ∝ n
Principal quantum number has always a positive integer value ( n = 1, 2, 3, …) and it helps us to identify the shell.
n |
1 |
2 |
3 |
4 |
Shell |
K |
L |
M |
N |
Magnetic quantum number determines the number of preferred orientations of the orbitals in a subshell. It is donated by ‘mℓ’. The mℓ can have (2l+1) values ranging from -l to +l (all the integer values including 0). Magnetic quantum number describes the behaviour of electrons in a magnetic field.
The electron spin quantum number is independent of the values of n, l, and mℓ. The value of this quantum number, which denotes the direction in which the electron is spinning, is represented by the symbol "ms". The direction of the electron's spin can be determined by looking at the value of ms. There are two possible values for the electron spin quantum number: 12 and -12.
Value for l |
Subshell |
Description |
Shape |
0 |
s |
Sharp |
Spherical |
1 |
p |
Principal |
Dumbbell |
2 |
d |
Diffuse |
Double-dumbbell |
3 |
f |
Fundamental |
Complex |
ħ=h2
Where l=azimuthal quantum number
Value for n |
1 |
2 |
3 |
4 |
Value for l |
0 |
0,1 |
0,1,2 |
0,1,2,3 |
Notation for subshell |
1s |
2s,2p |
3s,3p,3d |
4s,4p,4d & 4f |
Number of subshell |
1 |
2 |
3 |
4 |
Orbital angular momentum = l(l+1) h2 |
0 |
h2 |
6h2 |
3h2 |
The orbital diagram of Mg:
The orbital diagram of O-:
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Answer: C
Solution: The two electrons occupying the same orbital can never have the same spin. The spin quantum number can be either +12 or-12 and distinguishes the two electrons present in the same orbital.
So, option C is the correct answer.
Answer: D
Solution: Since n=3 (principal quantum number) and l=1 (azimuthal quantum number), it is a 3p-orbital, and since mℓ=0 (the magnetic quantum number) the given 3p-orbital is 3pz. As a result, the given quantum numbers can only identify a maximum of one orbital i.e. 3pz.
So, option D is the correct answer.
Answer: C
Solution: n=3,l=1 and mℓ=1 implies that it is an orbital of the 3p subshell. Any orbital can have a maximum of 2 electrons with spin quantum number ± 12. Therefore, the maximum number of electrons with n=3,l=1,mℓ=1 is 2.
So, option C is the correct answer.
Answer: A
Solution: n=3 and l=1 implies that it is an orbital of 3p subshell. 3p shubshell contains 3 orbitals and each orbital can have 2 electrons. Therefore the quantum numbers n=3 and l=1 can hold a maximum of six electrons.
So, option A is the correct answer.
1. The principal quantum number can not have which value?
Answer: The value of the principal quantum number (n) can never be zero. The permitted values for n are 1, 2, 3, 4, and so forth.
2. Which quantum number determines the shape of an orbital?
Answer: The integer value of the angular momentum quantum number, l, can range from 0 to n - 1. The type or shape of the orbital is indicated by this quantum number.
3. What is the source of quantum numbers?
Answer: Atomic orbitals are precisely distinguished by quantum numbers. These quantum numbers are obtained from the solution of the Schrodinger wave equation.
4. What are degenerate orbitals?
Answer: Orbitals having the same energy are called degenerate orbitals. Lower energy levels are filled before higher energy levels, according to the Aufbau principle.
Related Topics
Millikan’s oil drop experiment |
Discovery of neutrons |
De Broglie's Hypothesis |
Thomson's atomic model |
Quantum numbers |
Rutherford's Atomic Model |