Explaining Quantum Numbers

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Explaining Quantum Numbers

Postby JaylinWangDis1L » Sun Nov 01, 2020 5:31 pm

Can someone explain the quantum numbers (angular momentum, magnetic quantum number)? I know what they represent and their allowed values but how do you go about figuring them out from electron configurations?

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Re: Explaining Quantum Numbers

Postby HilaGelfer_2H » Sun Nov 01, 2020 5:41 pm


Since quantum numbers represent a certain a state for the electron, knowing the electron configuration you'd have to know which shell/subshell the question was referring to so you could write the correct quantum numbers for that state. Once you know which state you referring to you can decipher the correct quantum numbers representing that state. For instance, if you needed the quantum numbers for 2px^1. You would know that it is on the second shell, meaning n=2. Since you are in a p orbital you know the matching l value to represent a p orbital is 1. Additionally, depending on how the question labels x,y, and z for the ml quantum number you can figure out whether the ml value would be -1,0 or 1. Lastly, for the electron spin value you can decide whether it it was .5 or -.5 based on the information given in the question.

I hope this helps :)

Can Yilgor 2D
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Joined: Wed Sep 30, 2020 10:09 pm

Re: Explaining Quantum Numbers

Postby Can Yilgor 2D » Sun Nov 01, 2020 5:50 pm

Principal Quantum Number (n) determines ENERGY and SIZE of an orbital.
Angular Momentum Quantum Number (l) describes the SHAPE of an orbital.
Magnetic Quantum Number (ml) labels different orbitals of a subshell. It gives the ORIENTATION of the angular momentum.

If we take 4s orbital as an example,

l=0 Since (l=0, s-orbital) (l=1, p-orbital) (l=2, d-orbital)
ml=0 Since there is only one s-orbital

Hope this helps

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