A diagram of Rubidium atom looks like this:

[![enter image description here][1]][1]

The outer layer electron is on the energy level of 5S. But today when I try to read some papers working with Alkaline atom, I couldn't figure out how they plot the Rubidium energy level. From my undergraduate study, I thought it should be something like this:

[![enter image description here][2]][2]

The spin up and spin down electrons occupied the energy levels from ground state go upward. But I really cannot figure out the diagrams below:

[![enter image description here][3]][3]

and

[![enter image description here][4]][4]

and

[![enter image description here][5]][5]

So my questions are:

 - How could the 6S and 7S energy levels be occupied?
 - What does the subscript $S_{1/2}$ and $P_{3/2}$ means? Does this means spin? But electron should only have spin number $\pm 1$, right?
 - What is the F quantum number? It is not the F from the "spdf" orbital notation, right?
 - Can anyone draw a diagram of ${ }^{87} \mathbf{R b}$ with all **energy levels** and the **relationship between different quantum numbers**? 

Thanks for any help!


  [1]: https://i.sstatic.net/8cjB5.jpg
  [2]: https://i.sstatic.net/BX6sq.png
  [3]: https://i.sstatic.net/ALxCo.png
  [4]: https://i.sstatic.net/qmZ0r.jpg
  [5]: https://i.sstatic.net/eWx5G.jpg