## s,p,d,f

Matia Kim 1B
Posts: 60
Joined: Fri Apr 06, 2018 11:03 am

### s,p,d,f

Why does the number order change going from S to D? 4s to 3d instead of 4d?

sameeksha_panda_3h
Posts: 31
Joined: Fri Sep 28, 2018 12:25 am

### Re: s,p,d,f

Idk if this answers your question but when filling up the subshells, the 4s subshells fills up before the d orbital does.

Kessandra Ng 1K
Posts: 67
Joined: Fri Sep 28, 2018 12:25 am

### Re: s,p,d,f

This is because the 4s sub-shells are of a lower energy than the 3d ones so that's why the electrons fill the 4s ones up first.

Carlos De La Torre 2L
Posts: 60
Joined: Tue Oct 09, 2018 12:16 am

### Re: s,p,d,f

It is because, in terms of energy level, 3D is closer in energy to 4S orbital, than 4D thus when being filled with electrons it is written where it is

Chloe Likwong 2K
Posts: 70
Joined: Fri Sep 28, 2018 12:23 am

### Re: s,p,d,f

Also, remember after filling in the electrons in the order of 4s & 3d, you should move 3d before 4s. So, it will be 3d^n, 4s^n in your final electron configuration.

Joussie Camacho 4I
Posts: 33
Joined: Tue Oct 02, 2018 12:16 am

### Re: s,p,d,f

How do you know that/when the d-orbital has to fill before the s-orbital? For example, why is the electron configuration of Cu+: [Ar]3d^10 rather than [Ar]3d^94s^1.

Is it whenever the d-orbital has either 4 electrons (one in each orbital) or 9 electrons (all but one orbital are spin paired) that you take electrons from the s-orbital in order to fill the d-orbital first?

Joussie Camacho 4I
Posts: 33
Joined: Tue Oct 02, 2018 12:16 am

### Re: s,p,d,f

How do you know that/when the d-orbital has to fill before the s-orbital? For example, why is the electron configuration of Cu+: [Ar]3d^10 rather than [Ar]3d^94s^1.

Is it whenever the d-orbital has either 4 electrons (one in each orbital) or 9 electrons (all but one orbital are spin paired) that you take electrons from the s-orbital in order to fill the d-orbital first?

AJ Manzano 3K
Posts: 16
Joined: Fri Sep 28, 2018 12:25 am

### Re: s,p,d,f

An empty 4s has lower energy than an empty 3d. However, when they're filled 4s has a higher energy than 3d. Hence the reason why you write 3d before 4s in the final configuration.

kimberlyrose1G
Posts: 44
Joined: Fri Sep 28, 2018 12:27 am

### Re: s,p,d,f

Matia Kim 1B wrote:Why does the number order change going from S to D? 4s to 3d instead of 4d?

In electron configurations, the order goes by principle quantum number (n) so for the most part 3d will go before 4s, except for the elements Chromium ([Ar]4s^1 3d^5) and Copper ([Ar] 4s^1 3d^10) in order for these atoms to be in their most stable form

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