## Not understanding the use of ml

Dahriel Aron 3A
Posts: 60
Joined: Fri Sep 25, 2015 3:00 am

### Not understanding the use of ml

I do not fully understand the quantum value of ml. Does it determine if an element is magnetic or does it determine the orbital? Also, say that n=4, l=2, and ml=-2. How would I use that information to determine how many electrons can have those quantum numbers in an atom?

Crystal Eshraghi 2L
Posts: 24
Joined: Fri Sep 25, 2015 3:00 am

### Re: Not understanding the use of ml

From what I understand, ml refers to the magnetic quantum number and determines the orientation of the orbital in question by labeling the different orbitals of a subshell with specific numerical values. Since ml can take the any value within the range of -l to l, each of those values would correspond to a particular plane in which the orbital is located. For example, for l = 1 (thus corresponding to a p-orbital), ml = 1 could represent the px plane, ml = 0 could represent the py plane, and ml = -1 could represent the pz plane.

Chem_Mod
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### Re: Not understanding the use of ml

Crystal is correct.

In addition, the Pauli exclusion principle states that no two electrons can have the same set of all four quantum numbers. If n=4, l=2, and ml=-2 then the only quantum number left that can vary is the spin, of which there are only two states. Therefore only two electrons in an atom can have these quantum numbers (and these two would have opposite spin)