Sequen of Orbitals

[Natalie LeRaybaud 1G]

Are we always supposed to put the 4s orbitals after the 3d? Because in high school I'm pretty sure we learned to write out 4s then 3d.
For example the electron configuration for Gallium I thought would be Ga: [Ar] 4s2 3d10 4p1 but are we now supposed to write it as Ga: [Ar] 3d10 4s2 4p1 ? And if so why?

[Alex Kashou]

Yes we are supposed to put the 4s after the 3d. This is because we are going by increasing energy levels and the 3d subshell is lower energy. However, the 4s subshell fills up before the 3d which is why in highschool we learned to write it 4s3d.

[Ramya Natarajan 1D]

I'm fairly sure it's just a different way of ordering it but with the same logic. So yes, the 4s comes first, but in our final answer we rearrange the sequence in numerically ascending order?

[Ashley Davis 1I]

If this is true then why, for elements like tungsten, would it be 4f14 5d4 6s2 instead of 4f14 5s2 5p6 5d4 6s2?

[aTirumalai-1I]

[Xe] 4f^14 5s^2 5p^6 5d^4 6s^2 wouldn't make sense in this case because the "[Xe]" already accounts for the electrons in the 5s and 5p orbitals. Thus the electron configuration would simply be [Xe] 4f^14 5d^4 6s^2.