Tell which of the following combinations of quantum numbers are not allowed. Explain your answers.
(a) n = 3, l = 0, ml = -1
(b) n = 3, l = 1, ml = 1
(c) n = 4, l = 4, ml = 0

Question

Accepted Answer

Hey everyone in this example we need to identify the incorrect set of quantum numbers. When it comes to quantum numbers we have a few different values. Our end value is representative of our energy level or our shell number. We also have the quantum number represented by the symbol L. And this represents our azimuth slash angular quantum number. And then we also have our ml value here which represents our magnetic quantum number. Now we should recall that our ml values will range from negative L. Two, positive L. And then we should recall that our L values will be represented by our energy level -1. So let's go ahead and analyze our answer choices. We're told that we're at the fourth energy level in part A. So to determine our angular or as a quantum number L. We would take 4 -1 which would give us three. So this is correct. And then for our ml value this is going to be again from negative L. Two, positive L. So we would cover negative three negative two A negative one. And we do have negative one listed. So we can go ahead and rule out choice A. Because this is a correct set of quantum numbers. Moving onto choice B. We're told we're at the third energy level. Our angular quantum numbers too. So that's found from N 3 -1 which does give us two. So this is correct. And then our magnetic quantum number should cover all the way up to positive two and we are given positive one which is right before positive two. So this would definitely be a correct set and we can rule out choice B. Next we have choice C. Which tells us we're at the second energy level for our angular or as a quantum number we take n minus one. So that's two minus one which does give us one. So L. Is a correct value here and then for ml value we should cover all the way up to or all the way from negative one up to positive one And we are given -1. So this is also another correct set. Moving on to choice D. We are told were at the first energy level to find our L. Value we should take one minus one. So this gives us an L. Value. Actually that should be zero. So this needs to be corrected here. This is wrong. And then moving on to our magnetic quantum number that should cover from just zero. And so that part is correct. But our angular or as a mutual quantum number here as one is incorrect because again we have the first energy level minus one to get the L. Value which should give us zero. So our only correct choice would be D. Because it's the only correct set of quantum numbers or incorrect set of quantum numbers. So I hope that everything I reviewed was clear. If you have any questions please leave them down below and I will see everyone in the next practice video

Tell which of the following combinations of quantum numbers are not allowed. Explain your answers. (a) n = 3, l = 0, ml = -1 (b) n = 3, l = 1, ml = 1 (c) n = 4, l = 4, ml = 0

Verified Solution

Key Concepts

Quantum Numbers

Principal Quantum Number (n) and Azimuthal Quantum Number (l)

Magnetic Quantum Number (ml)