Spectrum of Sodium vs. Hydrogen

  • Thread starter roam
  • Start date
  • #1
roam
1,271
12
My question is: Why the energy levels for sodium are different from those for hydrogen even though sodium is described as a "hydrogen-like atom"?

Here I have posted the energy diagrams for sodium, and hydrogen.

So, I have noted that sodium has 11 protons, whereas the hydrogen has only 1 proton. So sodium has a heavier nucleus having a charge 11 times greater than that of hydrogen. And sodium has 11 electrons while hydrogen has only 1.

I wanted to argue that the difference of the number of protons and electrons somehow affects the spin-orbit coupling. But in sodium the nucelus with Z=11 is "screened" by 10 negative charges. So we have 1 free electron, exactly like the hydrogen atom! So shouldn't we end up with the same energy diagram? :confused:

I am very confused about this. Any explanation would be greatly appreciated.
 

Answers and Replies

  • #2
Bill_K
Science Advisor
Insights Author
4,157
203
It's because Sodium starts out with 10 extra electrons that fill up the lowest shells. Therefore these levels aren't available to the valence electron. Cover over the lowest levels of Hydrogen (principal quantum number 1 and 2), and you'll see that Sodium levels match a subset of Hydrogen levels.
 

Suggested for: Spectrum of Sodium vs. Hydrogen

Replies
3
Views
414
Replies
9
Views
523
Replies
4
Views
519
Replies
2
Views
326
Replies
18
Views
731
Replies
11
Views
453
Replies
4
Views
395
Replies
22
Views
661
Replies
7
Views
460
Replies
4
Views
195
Top