## The 4 Quantum Numbers [ENDORSED]

William Lan 2l
Posts: 73
Joined: Fri Sep 29, 2017 7:07 am

### The 4 Quantum Numbers

Can someone briefly go over the 4 quantum numbers? (n, l, m subscript l, and m subscript s)?

Im stuck specifically with l and m subscript l. What do they mean and what do they show?

Deborah Cheng 1F
Posts: 50
Joined: Thu Jul 13, 2017 3:00 am

### Re: The 4 Quantum Numbers

n is the principal quantum number that indicates shell and energy level. The higher the value n, the larger the orbital is.
l is the angular quantum number that indicates sub-shell and shape of the orbital (s, p, d, or f)
m sub l is the magnetic quantum number that specifies the orientation of the orbital in space
m sub refers to the electron spin and can have two values: +1/2 or -1/2
If you look at page 36 of the textbook, there is a table that gives a little summary of what each means, hope this helps!

Posts: 58
Joined: Fri Sep 29, 2017 7:04 am

### Re: The 4 Quantum Numbers

Is there a specific orientation for the quantum numbesr in m sub l?

Suchita 2I
Posts: 59
Joined: Fri Sep 29, 2017 7:04 am

### Re: The 4 Quantum Numbers  [ENDORSED]

Yes, the orientation of the orbital (the magnetic spin quantum number) depends on the angular quantum number which specifies whether it is an s, p, d, or f sub-level. For example, the s sub level only has 1 orbital, while the p sub level has 3 orbitals (px, py, and pz) which differ in their spatial orientation. That is, the 3 orbitals of the p sub level are 3 dumb-bell shaped orbitals oriented along the x, y and z axes. The different spatial orientations of the orbitals get more complex for the d and f sub levels which have 5 and 7 orbitals, respectively. Hope this helps!

Alexia Joseph 2B
Posts: 56
Joined: Thu Jul 27, 2017 3:01 am

### Re: The 4 Quantum Numbers

Can someone describe more about how to deduce what l and m sub l is when you know what n is? I'm still kind of confused.

kaushalrao2H
Posts: 63
Joined: Thu Jul 13, 2017 3:00 am
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### Re: The 4 Quantum Numbers

Lets say that we are describing a valence electron in Aluminum. The principle quantum number (n) would be 3, the angular momentum quantum number (l) would be 1 (because 1 signifies the p orbital), the magnetic quantum number (m sub l) would be -1 (because the ml numbers -1 0 and 1 represent the px, py, and pz orbitals within the p subshell), and the spin magnetic quantum number (m sub s) would be -1/2.