Electron Configurations for d-orbital

[Meagan Kimbrell 1I]

I understand that Professor Lavelle wants us to write down the d-orbitals before the s-orbitals when writing configurations, but I had never learned this before. I had always written s before d.
Is d before s a standard practice? Or were my high school teachers just not teaching me correctly?

[Anna Dai-Liu 3B]

I don't think he necessarily said d before s - 3d comes before 4s for first-row transition metals because in those atoms the d orbital of the previous shell has a lower energy than the s orbital of the next orbital, but 4d doesn't come before 4s.

[Sarah Wang 1I]

Electrons usually enter the 4s orbital before 3d because 4s is initially lower in energy. But, for the elements from Scandium and onward, the 3d orbital has lower energy than 4s, which is why 3d is written before 4s in the configuration.

[Stephanie Trinh 1F]

With 4s and 3d for example, 4s has less energy when they are not filled with electrons, but as they are filled with electrons, 3d actually becomes lower in energy than 4s and that is why it is written in that order.

[Nandini_Parmar_1I]

From what I have noticed in Professor Lavelle's class, he writes it in order according to principle quantum number which is represented by the shells. So in order of number basically :).

[Hope Galarneau 1A]

The reason that you would write d before s is because it has a lower energy state than the s orbital once it begins to fill with electrons. Thus, when writing the configurations, the d orbital should go before the s orbital because of its energy. This will make it so that 3d goes before 4s, 4d before 5s, etc.

[Russell Chuang 1J]

I think it is written d before s in situations like 3d then 4s because 3d has a lower energy level. 4s has a higher energy level, meaning that it should be placed after.

[305749341]

I think it is just a notation preference that Dr. Lavelle has because my AP Chemistry teacher did not care if we wrote s before d orbital. However, Dr. Lavelle is helping us understand that the s orbital has more energy and is further away from nucleus. The s orbital with higher principle quantum number will be in the outermost shell of the atom whereas a d orbital would be closer to the core.