Question

I have having difficulty understanding where L comes from in term symbol notation

For Carbon, e- configuration is 1s^2 2s^2 2p^2

p corresponds to l=1
overall spin is 3/2
since cell is less than half-full, J=S=3/2

so term symbol is 4 P (3/2)

this i understand where P came from
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But for Nb2+ where it is 4d^3

It is 3 F (4)

Isn't d corresponding to l=2

so shouldn't it be 3 D (4)?

Answer 1

Isn't the ground state of carbon ³P_o

Answer 2

You are correct DrBob. Error on my part.

Answer 3

But for Nb2+ where it is 4d^3

Shouldn't L be D instead of F?

Like p^2 in carbon, L = P

And in s^2, L = S

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Or am I going about this the wrong way?

Answer 4

No, L = 3.
You have 3d electrons, they occupy M_l =
+2---+1---0
Add 2 + 1 + 0 = 3 which is F.
When you had 4d4 5s1 (in the neutral Nb) it is figured as
+2--+1--+0-- -1 --
So you add +2+1+0-1 for the d electrons and 0 for the s electron and the total is 2 which is D.

Answer 5

what about Nb2+ then?

it has 8 electrons
it occupies 2, 1, 0, -1, -2

so would that make L = 0 which is S?

Answer 6

Have you confused yourself?
Your earlier post said Nb^+2 was 4d3 and that is correct. So where do you get this 4d8 stuff?
If Nb is 4d4 5s1, then remove the 5s and 1 of the 4d to make Nb^+2 and that leaves Nb^+2 = 4d3 for which
2 + 1 + 0 = 3 and that is F.

Answer 7

Thank you Dr Bob. Yes, I am seriously confusing myself haha

As far as the 4d8 is concerned, I was referring to Ni2+

it has 8 electrons
it occupies 2, 1, 0, -1, -2

so would that make L = 0 which is S?


Sorry for the confusion. I greatly appreciate you staying and helping me despite my many errors.

Answer 8

OHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.

if it was 8e- in d orbitals (5 of em)

it would be +2 +1 0 -1 -2 for up spin , then +2 +1 and 0 for down spin!

therefore, total is 3 and L=3!!!!

I hope this is correct!

Answer 9

Your OHHHHH is right on. L = 3
There are two unpaired electrons; therefore, s = 1/2 + 1/2 = 1 and M = 2S + 1 = 3
L = 3
and since the d shell is more than half filled, J = L + S = 3 + 1 = 4 so
³F₄ is the term symbol. By the way, you can check any element by going to www.webelements.com, clicking on the element, scrolling down and slicking on electronic properties, then scrolling down to see the electronic configuration and the term symbol.
Here is the Ni^+2 (but Ni neutral element) is the same.

Answer 10

Dr Bob,

Thank you so much!! You have taught me something in mere minutes that my professor failed to do in a single lecture. And thank you again for the web site. I had no idea such a site existed!

I wish there was a karma/rep system :)

thanks again