Question

When assigning electrons to orbitals, which would be the most likely 'address' for the next electron following the 5s2 electron?

Answer 1

An easy way to remember where electrons will be found/distrubuted is as follows:



We begin filling from the most stable, the 1s orbital, outwards to less and less stable orbitals, following the path of the arrow on each occasion.

So, we will get 1s, 2s, 2p, 3s, 3p, 4s, 3d,..... as being the order of filling the orbitals.

The incomplete arrows indicate that there are further orbitals below to be filled before we move onto the next arrow. I have not listed them all, but the diagram show that once we fill the 5s orbital (i.e. we have filled orbitals up to as far as 5s2), we have reached the end of an arrow and must now follow the path of the next one. You should be able to now work out what the 'address' or the orbital for the next electron to be added. Hope this trick works!