D and S oribitals

[Sunjum Singh 1I]

So for all electron configurations of elements is the D-orbital always before the S-orbital?

[Adrienne B 1J]

hi! usually for most energy levels the s orbitals are filled before moving on to d orbitals :)

[Marisol Sanchez - 1E]

I believe in most cases the S orbital is filled up before the D orbital at least for the first few periods. Once you reach the fourth period, the electrons fill up the first two spaces in the 4s orbital but then go back to start filling up the D orbitals of the 3rd shell. So to my understanding, the S orbital always goes first but depending on where in the periodic table you are working, you will either proceed to the P orbitals of that same shell or revert back to the D orbitals of the previous shell which as mentioned begins to occur once we get to the fourth period. This has to do with the relative energies that occur based on the positioning because the S orbital of a higher shell technically has less energy than the D orbital of a lower shell I believe.

[Luis Avalos 1D]

If you're asking about writing them out, it's a personal preference I believe. For example, some people would write scandium as [Ar] 4s² 3d¹ but others write it as [Ar] 3d¹ 4s²