Angular Momentum Quantum Number
Definition and meaning of Angular Momentum Quantum Number in chemistry.
The angular momentum quantum number is a quantum number specifying the orbital angular momentum of an electron in an atom, determining the shape of its orbital. It takes integer values from 0 to n−1, where n is the principal quantum number.
In more detail
Each value of the angular momentum quantum number corresponds to a different orbital type: l = 0 produces s orbitals (spherically symmetric), l = 1 produces p orbitals (dumbbell-shaped), l = 2 produces d orbitals, and l = 3 produces f orbitals. Combined with other quantum numbers, it fully specifies an electron's quantum state and spatial distribution. The symbol for this quantum number is l or ℓ.
Key facts
| Symbol | l or ℓ |
|---|---|
| Field | Physical Chemistry |
| Possible values | 0 to n−1 (integers) |
| Orbital shapes | s (l=0), p (l=1), d (l=2), f (l=3) |
An electron in a 2p orbital has a principal quantum number n = 2 and an angular momentum quantum number l = 1, indicating occupation of a p orbital in the second electron shell.
Frequently asked questions
How does the angular momentum quantum number relate to orbital shape?
Each value of l determines a distinct orbital shape, s orbitals are spherical, p orbitals are dumbbell-shaped, d orbitals are cloverleaf-shaped, and f orbitals are more complex multi-lobed shapes.
What limits the values the angular momentum quantum number can take?
The angular momentum quantum number can only range from 0 to n−1, so higher principal quantum numbers allow more orbital types to exist in that shell.