Quantum numbers and Periodic table II/. What is an orbital? It is the space around the nucleus in which the electron is found with a probability of 90%.

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

Faculty of art

chem

Faculty of engineering

Faculty of science

phys MathMech civilArabic Engl.

D BM M MMBB M BM B B

1 2 3

a b c d e f g

Each student in the university is defined by a set of symbols:

A Math student in the master program has the set: 3 g

Mainshells

sub-shells

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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

Principal Quantum Number n 1, 2, 3, 4, …….

-Gives the main shell in which the electron exists.

-Determines largely the energy of the electron.

-Determines the size of the orbital.

Azimuthal (secondary, angular moment) Quantum

Numberℓ 0, 1, 2, …, (n-1)

-Gives the subshell in which the electron exists.

-contributes to energy of electron.

-Determines the shape of the orbital

Magnetic Quantum Number mℓ -ℓ, …, 0, … +ℓ -Determines the orientation of orbital in space

Spin Quantum Number ms +/- 1/2 -orientation of rotation of electron around itself.

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l-value orbital type

0 s

1 p

2 d

3 f

4 g

5 h

n-valueMain shell designation

1 K

2 L

3 M

4 N

5 O

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n ℓ(n-1)

mℓ

(-ℓ, …, +ℓ)

No. of orbitals

No. of electrons

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

18

4 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

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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3p1 node

Number of nodes: n-ℓ-1 3s: 3-0-1=2 nodes2s: 2-0-1=1 node1s: 1-0-1= 0 node2p: 2-1-1= 0 node3p: 3-1-1=1 node3d: 3-2-1=0 node

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