What is l, ml, and ms I'd n=4?

##l = 0, 1, 2, 3##. ##m_l = -3, -2, -1, 0, 1, 2, 3## ##m_s = +1/2## or ##-1/2##

I assume that you're talking about the .

So, if you're not familiar with the concepts behind quantum numbers, I'd recommend you take a look at this video first. If you're good, let's go...

So to quickly recap here's what each quantum number describes:

##n## = energy level. ##l## = subshell; ranges from 0 up to ##n-1## ##m_l## = orbital; ranges from ##-l## to ##l## ##m_s## = tells the spin of the electron; is either ##+1/2## or ##-1/2##

Now, your question asks what are the possible values for ##l##, ##m_l##, and ##m_s## for ##n = 4##. So, let's just work through this from top to bottom.

Firstly, if ##n=4##, let's consider what ##l## could be. We know that ##l## ranges between 0 to ##n-1##. Therefore, we can say that:

##l = 0, 1, 2, 3##.

Side note: this essentially means that the n=4 energy level can hold electrons in the s, p, d and f subshells

Okay, so now that we know all possible values of ##l##, let's look at ##m_l##. We know that ##m_l## ranges between ##-l## and ##l##. But which of the above ##l##'s do we use? Well, consider this: if we just looked at the highest value of ##l## present, it would take care of all the lower ones. See what I mean below:

##m_l = -3, -2, -1, 0, 1, 2, 3##

See how values like ##-2## and ##1## are taken care of?

So, that's really it. ##m_s## will only be either ##+1/2## or ##-1/2## regardless of the other 3 quantum numbers.

Hope that helped :)