Magnetic Quantum Number
Definition and meaning of Magnetic Quantum Number in chemistry.
The magnetic quantum number (ml) is a quantum number that specifies the spatial orientation of electron orbitals in three-dimensional space around the nucleus.
In more detail
For each value of the orbital angular momentum quantum number (l), the magnetic quantum number (ml) can take integer values ranging from -l to +l. For instance, in a p orbital (l=1), the magnetic quantum number can be -1, 0, or +1, corresponding to the three distinct spatial orientations of the orbitals. The term "magnetic" arises because these orbitals are distinguishable in the presence of an external magnetic field, as demonstrated by the Zeeman effect. The number of possible ml values for a given l is always 2l+1, which equals the number of orbitals in that subshell.
Key facts
| Field | Physical Chemistry |
|---|---|
| Symbol | ml |
| Possible Values | Integer values from -l to +l |
| Orbitals per Subshell | 2l + 1 |
In a 2p subshell (where n=2 and l=1), the magnetic quantum number can have three values: ml = -1, 0, or +1. These correspond to the three different p orbital orientations in space.
Frequently asked questions
Why is it called the 'magnetic' quantum number?
It is called magnetic because these orbitals have different energies when exposed to an external magnetic field, as shown in the Zeeman effect.
How many values can the magnetic quantum number have for a given orbital angular momentum?
For a given value of l, the magnetic quantum number can have 2l+1 possible values, which corresponds to the number of orbitals in that subshell.