1. Quantum Numbers
Part Two

2. Magnetic
Describes the orientation of the subshell on the x, y, and z axis
A specific orientation of a subshell is called an orbit
The magnetic quantum number tells us which orbit the electron is in within the subshell
Represented by mℓ

5. Hund’s Rule
Electrons will spread out to all the possible orbits within a subshell before they double up.

6. Spin
Describes the spin of the electron within the specific orbit
Represented by ms
Pauli exclusion principle: There can only be two electrons per orbit and they must spin in opposite directions
ms = +1/2 or -1/2

7. How we show the quantum numbers
We illustrate an element’s quantum numbers using electron configurations.
Examples:
Hydrogen: 1s
Helium: 1s
Lithium: 1s s
Neon: s s 2p 1 2
2 1

8. 1s
2s 2p
3s 3p 3d
4s 4p 4d f
5s 5p 5d f
6s 6p 6d f
7s 7p 7d f

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Gold: 79e
1s 2s 2p
3s 3p 4s
3d 4p 5s
4d 5p 6s
4f 5d
1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f

10. Orbital Diagrams
Another method used to illustrate an element’s quantum numbers is orbital diagrams:
Examples:
Hydrogen ___
Helium ___
Lithium ___ ___
Neon ___ ___ ___ ___ ___ 1s
1s 2s
1s 2s 2p