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Quantum numbers and
Periodic table
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What is an orbital?
• It is the space around the nucleus in which the electron is found with
a probability of 90%.
• The electron spends 90% of its time in that space.
90%
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Different shapes of orbitals
s
p
d
f
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university
1
2
Faculty of art
Faculty of
engineering
a
b
Arabic
g
D
B
M
c
Engl.
a b
b
M
3
g
B
b
M
Faculty of science
d
Mech
g
B
Main
shells
civil
b
e
chem
g
M
B
g
f
phys
Math
g b
g
B
B
b
M
subshells
M
Each student in the university is defined by a set of symbols:
A Math student in the master program has the set: 3
gb
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Similarly, electrons in atom are specified by a set of numbers, the
quantum numbers:
The Quantum Numbers
name
symbol
values
Physical significance
-Gives the main shell in which the electron
exists.
Principal Quantum Number
n
1, 2, 3, 4, …….
-Determines largely the energy of the electron.
-Determines the size of the orbital.
-Gives the subshell in which the electron exists.
Azimuthal (secondary,
angular moment) Quantum
Number
ℓ
0, 1, 2, …, (n-1)
-contributes to energy of electron.
-Determines the shape of the orbital
Magnetic Quantum Number
mℓ
-ℓ, …, 0, … +ℓ
Spin Quantum Number
ms
+/- 1/2
-Determines the orientation of orbital in space
-orientation of rotation of electron around itself.
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l-value
orbital type
0
s
1
n-value
Main shell
designation
p
1
K
2
d
2
L
3
f
3
M
4
g
4
N
5
h
5
O
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ℓ
mℓ
(n-1)
(-ℓ, …, +ℓ)
No. of
orbitals
1
0 (s)
0
1
2
2
2
0 (s)
1 (p)
0
-1, 0, 1
1
3
2
6
8
3
0 (s)
1 (p)
2 (d)
0
-1, 0, 1
-2, 1, 0, 1, 2
1
3
5
2
6
10
0 (s)
1 (p)
2 (d)
3 (f)
0
-1, 0, 1
-2, 1, 0, 1, 2
-3, -2, 1, 0, 1, 2, 3
1
3
5
7
2
6
10
14
n
4
No. of
electrons
18
32
2n2
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Nodes: Regions where electrons are not allowed to be present in.
Electron Probability of being there is zero.
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3p
1 node
Number of nodes: n-ℓ-1
3s: 3-0-1=2 nodes
2s: 2-0-1=1 node
1s: 1-0-1= 0 node
2p: 2-1-1= 0 node
3p: 3-1-1=1 node
3d: 3-2-1=0 node
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