One electron has a four-part address
Think of an address containing a building, room type, room direction,
and one of two seats. Quantum numbers identify an electron in a similar way.
1. Shell — n
Values are 1, 2, 3 and higher. It describes the principal energy level
and the approximate size of the electron cloud.
2. Shape — l
The shape number ranges from 0 to n − 1. The names are:
s for 0, p for 1, d for 2 and f for 3.
3. Direction — mₗ
This number ranges from −l to +l. It selects an orbital's orientation
in three-dimensional space.
4. Spin — mₛ
Spin has only two allowed values: +½ and −½. Two electrons in the same
orbital must have opposite spins.
What the probability cloud means
The cloud is not a physical fog or circular electron path. Dense regions
represent locations where the electron is more likely to be detected.
Suggested investigations
- Compare shell 1 with shell 4 and observe cloud size.
- Compare spherical s, dumbbell p and clover-shaped d orbitals.
- Change the direction number and rotate the orbital.
- Compare nitrogen and oxygen to investigate spin pairing.
- Use iron to explore a 3d electron.