Question

Which sublevel is filled after the 5s sub level?

Answer 1

The 4d sublevel is filled next, after the 5s sublevel.

Explanation:

Electrons fill the sub levels in energy order:
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p

If we add the number of electrons that each sublevel holds it looks like this:
`1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^10 5p^6 6s^2 4f^14 5d^10 6p^6 7s^ 2 5f^14 6d^10 7p^6`

Source: http://www.kentchemistry.com/links/AtomicStructure/Sublevels.htm

The Aufbau diagram can be memorized more easily than the electron configuration of all the sublevels up to `7"p"^6"`.