## Magnetic Quantum Numbers & Orbital Orientation

Abigail Urbina 1K
Posts: 102
Joined: Thu Jul 27, 2017 3:01 am

### Magnetic Quantum Numbers & Orbital Orientation

I understand that the allowed values for the magnetic quantum number range from l,l-1,...-l, but once we solve what those values are, what exactly do those numbers tell us? I know that the magnetic quantum number labels different orbitals of a subshell in terms of their orientation, but how does their number directly indicate what an orbital's orientation will be?

For example, if l=1, then the allowed values for magnetic quantum number are -1, 0, and +1. That would mean there are 3 p orbitals.

I know there is px, py, and pz, but how do we know which value corresponds to which orbital orientation?

soniatripathy
Posts: 50
Joined: Thu Jul 13, 2017 3:00 am

### Re: Magnetic Quantum Numbers & Orbital Orientation

principle quantum number (n): This tells you the energy level and corresponds to the period in the periodic table

azimuthal quantum number (l): This tells you the subshell and has possibilities of up to n-1. Here s=0, p=1, d=2, and f=3.

magnetic quantum number (ml): This tells you which part of the orbital you are in. The possibilities are -l to +l. For example if we look at the p orbital there are 3 possible electron areas for e- to be (px, py,or pz). ml has a value of -1, 0, or +1. Px, Py, and Pz are arbitrary assignments but we know that when e- are entering the same energy level in the same type of orbital, one e- will occupy each orbital before they begin to double up (Hund's rule).

spin quantum number (ms): This numbers tells you the orientation/spin or an electron. e- can spin up (+1/2) or down (-1/2).

For example, lets look at Nitrogen. Nitrogen has the following e- config.: 1s2 2s2 2p3 --> 1s2 2s2 2px1 2py1 2pz1. The quantum number for the last place/outermost e- will be n=2, l=1, ml=+1, and ms=+1/2