Quantum Numbers

[justadream]

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I was reviewing Quantum Numbers in EK Chemistry. I understand most ofit but one part confused me: the Second (Azimuthal) Quantum Number.

I understand what it represents the subshell. What I don't understand, however, is how the value of the 2nd Quantum Number is from "zero to n-1" where n is the period in the periodic table.

For example, in period 5, can the 2nd quantum number really range from 0 to 4? I know 0 = s, 1 =p, 2 = d, and 3 = f. What would "4" equal?

Another question: The books says the total orbitals within a shell is equal to n^2 where n is the period number (shell level). Applying this rule, the third period should have 3^2 or 9 orbitals. But I can only count 4 orbitals in the third period (1 s orbital and 3 p orbitals). What am I missing here?

Thanks for the help!

 

[vegaobscura]

An l of 4 would be a g orbital, but we don't have any of those in the current elements.

I'm not sure where you got that, but if you discount H and He as row 1, then work like that, You'd be missing the d orbitals! There are 5 d orbitals, with mls of +2, +1, 0, -1, -2.

I wouldn't think of it like that way, though--the n^2 thing--personally, that is. It's a little confusing.

Transition metals (and the things after the transition metals) have d orbitals. There are 5 d orbitals, like I said above. 2 electrons per orbital, makes for 10 electrons (and 10 transition metals) But they're not going to be your VALENCE electrons in anything.

4s electrons are farther out than your 3d electrons are (as are the 4p electrons, once you get down to that side of the periodic table).

 

[justadream]

So does the "n-1" thing only work in the first few periods?

I got all of this straight from the EK Chem book.

Thanks a lot for replying!

 

[SeminoleVesicle]

I was also confused about this. TBR does a great job of explaining this...if I remember correctly

s-block: 0
p-block: 1
d-block: 2

Please correct if me if I'm wrong.

 

[vegaobscura]

l --> orbital shell
0 - s
1 - p
2 - d
3 - f

And then, as far as where things go...

1s2
2s2 2p6
3s2 3p6 3d10 (3d for 1st row transition metals)
4s2 4p6 4d10 4f14 (4d for 2nd row transition metals) (4f for lanthanides)
5s2 5p6 5d10 5f14 (5d for 3rd row transition metals) (5f for actinides)
6s2 6p6

You should know how to fill those, but I'm not sure how much the MCAT is going to make you know about, say, the 4/5f orbitals.

As someone who was a Chemistry major--I don't even know much of anything about them.