Electron Configuration

[JTijerina_4A]

When we write electron configurations, do we write 3d, 4s or 4s, 3d?

[xenamclean_1G]

3d, 4s

[anjali41]

I think we are supposed to write them as 3D, 4S because it is then easier to see where the electron is being removed from in ions.

[AKhanna_3H]

Dr. Lavelle explained that the configurations should be written in order of energy level, so 3d would come before 4s.

[Yiyang Jen Wang 4G]

You should put 3d before 4s since when 3d is filled it has lower energy than 4s.

[Katie Phan 1K]

3d, 4s

[Yasmina Zaarour 1G]

One thing my AP Chem teacher taught us is that "last added doesn't necessarily mean last taken out." So in this example, the 3d is the "last added" since it is added in farther across the periodic table, but it's not necessarily the "last taken out"; if an electron were to be removed, the 4s electrons would be removed before the 3d electrons.

[joshtully]

I believe 3d comes before 4s.

[Savannah Torella 1L]

When it comes to electron configuration, you want to write the orbitals in the order that they were fully filled. In the context of your question, 3d would be written before the 4s since the 3d orbital is filled up first between the two.