# Exited states configuration

1. Nov 1, 2009

### Petar Mali

Litium has a structure

$$1s^22s^1$$

What is the first exited state of litium?

I have some doubt? I think that it is

$$1s^22p^1$$

Is it correct or maybe

$$1s^23p^1$$

Why I'm in problem. Because wave function of hydrogen atom depends of three quantum numbers
$$\psi_{n,l,m}$$ but energy depends only of one quantum number $$E_n$$. So we have degeneration. In this logic it's need to be $$1s^23p^1$$. But I don't have hydrogen I have litium, so must be some ecranisation and of course Hund rule $$s$$ and $$p$$ orbitals have different energy. And I can say that

$$E_{n,l}=-13,6eV\frac{1}{(n-\Delta l)^2}$$

2. Nov 1, 2009

3. Nov 3, 2009

Thanks!