## Writing electron configuration

Ying Yan 1F
Posts: 101
Joined: Fri Aug 02, 2019 12:16 am

### Writing electron configuration

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
Posts: 101
Joined: Sat Aug 24, 2019 12:16 am

### Re: Writing electron configuration

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

ranqiao1e
Posts: 51
Joined: Sat Sep 14, 2019 12:15 am

### Re: Writing electron configuration

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

Alexa Mugol 3I
Posts: 54
Joined: Sat Aug 17, 2019 12:17 am

### Re: Writing electron configuration

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
Posts: 102
Joined: Thu Jul 11, 2019 12:15 am

### Re: Writing electron configuration

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

PranaviKolla2B
Posts: 114
Joined: Fri Aug 30, 2019 12:17 am

### Re: Writing electron configuration

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

ABombino_2J
Posts: 102
Joined: Thu Jul 11, 2019 12:15 am

### Re: Writing electron configuration

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
Posts: 100
Joined: Sat Aug 17, 2019 12:17 am

### Re: Writing electron configuration

PranaviKolla3G wrote: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.