Writing electron configuration

[Ying Yan 1F]

When reaching the d block, which is the correct way to the write the electron configuration, 3d 4s or 4s 3d? I've noticed it written both ways, and it made me kind of confused. Thank you!

[005384106]

When writing electron configuration you need to write it in numerical order. So the correct answer would be 3d 4s. :)

[ranqiao1e]

The right way would be to write the 3D sub shell first

[Alexa Mugol 3I]

3d comes before 4s because 4s is higher in energy than 3d. Therefore, you would remove 4s electrons before 3d electrons (if 4s came before 3d it would be harder to tell which is the valence).

[ABombino_2J]

Whenever you are writing an electron configuration the orbital with the lower n should come first.

[PranaviKolla2B]

For an element like calcium, would the electron configuration end in 4s^2? And what about for Ca^2+?

[ABombino_2J]

Yes, for Ca the electron configuration would en with 4s^2. For Ca^2+, the electron configuration would end with 3p^6.

[Eunice Nguyen 4I]

For an element like calcium, would the electron configuration end in 4s^2? And what about for Ca^2+?

Calcium would end on 4s2. For Ca^2+, because you are removing electrons, it'll become 3p6.