## quantum numbers: m [ENDORSED]

Casey Dooley 2E
Posts: 34
Joined: Fri Sep 25, 2015 3:00 am

### quantum numbers: m

How do you find the m(l) quantum numbers. I know that if it is dependent upon the l number but how would you find it for a specific element. For example how would you know it for Fe. Also, for the spin how would you know if its -1/2 or 1/2?

Bryan Nguyen 1A
Posts: 20
Joined: Fri Sep 25, 2015 3:00 am

### Re: quantum numbers: m  [ENDORSED]

To find m, you have to find l first. l and m are both dependent on which block (s, p, d, or f) that the element is in.

In general l would be 0 in groups 1 and 2 (s-block), 1 in groups 13-18 (p-block), 2 in groups 3-12 (d-block; transition metals), and 3 for Cerium to Lutetium and Thorium to Lawrencium (f-block; Lanthanides and Actinides).

Fe is in the d-block so l would be 2 and m would be -2, -1, 0, 1, 2. Remember to list all of the possible numbers for m.

We can't say for certain which direction the electron of an element is spinning so if a question asks you to find $m_{s}$, then the answer would be "+1/2 or -1/2".

Prina Patel 1H
Posts: 62
Joined: Fri Sep 25, 2015 3:00 am

### Re: quantum numbers: m

The l value depends on which orbital gets filled last or the higher energy orbital the outer valence electrons occupy. Technically for Fe, the d orbital gets filled last even though it's placed before 4s^2 because its a higher energy orbital thus giving it the l number of 2 (s=0, l=1, d=2, f=3). m then is -2, -1, 0, 1, 2. for ms you can choose there is no rules for which ms value you can and can't use in a certain situation.

lena1217
Posts: 8
Joined: Wed Sep 21, 2016 2:58 pm

### Re: quantum numbers: m

I also have a question related to this. For the example we did in class on page 63 the answer is that the electron is in the 2px state. I understand why the electron is in the p state, but why is it in the "2" p state and how do we determine if it's in the x, y or z state?