s before d format

[LyahFitzpatrick 2E]

In class, professor Lavelle would write some configurations with the s orbital represented before the d one. Is there a reason for this? Does it matter?

[cecilia1F]

Hello,
I think this is to indicate that sometimes the s orbital has a lower energy level than the D orbital.

[005683006]

S orbitals have higher energy than d orbitals of the same shell, thus it is filled out first

[Meia Schram 1J]

^^this must be confusing hahah !

I do however have to agree with the first. I am pretty sure that the only reason s is filled out first is because it has a lower energy and we know that the lower levels are filled up quicker than the higher energy

[Chem_Mod]

After filling np orbitals, (n+1)s orbital is filled before nd orbitals since (n+1)s has lower energy than nd when they donot have electron in them.

Note: However, when we start to fill nd orbitals, they loose some energy and become with less energy than (n+1)s orbital, therefore for the configurations with d electrons, nd is written before (n+1)s. i.e. Fe: [Ar]3d⁶4s₂

[Ashwin Vasudevan 3A]

Hello,
Lower energy levels are filled first so that's why we start with the s orbital.

[Chem_Mod]

See the relative energies of the orbitals attached.

[arielle_cunanan3K]

According to this diagram, does that mean that the following s orbital is always filled up before the previous energy level- d orbital ?

[Ainsley DeMuth 1H]

The electron configuration is written out from lowest to highest energy and the d-block has more energy that the s-block. This is also seen through Aufbau's principle.