Spectrum of Sodium vs. Hydrogen

  • Thread starter roam
  • Start date
  • #1
1,266
11
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
4,155
199
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.
 

Related Threads on Spectrum of Sodium vs. Hydrogen

  • Last Post
2
Replies
31
Views
23K
  • Last Post
Replies
3
Views
9K
  • Last Post
Replies
5
Views
9K
  • Last Post
Replies
0
Views
3K
  • Last Post
Replies
18
Views
1K
Replies
10
Views
1K
  • Last Post
Replies
6
Views
9K
  • Last Post
Replies
2
Views
5K
Replies
2
Views
2K
Replies
1
Views
6K
Top