Question

Question #a7fdc

Answer 1

`m_l = 0`

Explanation:

Start by writing the electron configuration of a neutral sodium atom.

`"Na: " 1s^2 2s^2 2p^6 3s^1`

The last electron in a neutral sodium atom is added to the `3s` subshell, which, as you know, contains a single orbital, the `3s` orbital.

Now, the magnetic quantum number, `m_l`, tells you the orientation of the orbital in which an electron is located inside an atom.

In the case of an `s` orbital, the magnetic quantum number can only take one value.

`m_l = 0`

This is the case because the value of the magnetic quantum number depends on the value of the angular momentum quantum number, `l`.

`m_l = {-l, - (l-1), ..., -1, 0, 1, ..., (l-1), l}`

The angular momentum quantum number tells you the shape of the orbital(s), i.e. the energy subshell in which the electron is located.

An `s` subshell is denoted by

`l = 0`

which implies that the magnetic quantum number can only take one possible value here.

`l = 0 => m_l = 0`

This tells you that an `s` subshell contains a single orbital, the `s` orbital.