## Electron Configuration

$FC=V-(L+\frac{S}{2})$

Veronica Lu 2H
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Joined: Wed Sep 18, 2019 12:18 am
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### Electron Configuration

I am confused as to how we should order the electron configurations. I recall the correct order being like 4s2 then 3d10. However, in the textbook and midterm solutions it shows them being 3s2 3p6 3d10 then 4s2 4p6 etc. Which is right??

charleejohnson1L
Posts: 99
Joined: Fri Aug 30, 2019 12:17 am

### Re: Electron Configuration

When you write the configuration, you write it in the order of lowest to highest energy level. :) I hope this helps, this is what Lavelle said during lecture.

rabiasumar2E
Posts: 108
Joined: Thu Jul 11, 2019 12:15 am

### Re: Electron Configuration

4s would come after 3d!! In high school most of us learned to put the 4s before the 3d since they are in that order on the periodic table, but energy level wise the 4s would come after 3d. To put it simply, whenever you're doing electron configuration, put them in numerical order.

ramiro_romero
Posts: 90
Joined: Sat Sep 07, 2019 12:16 am

### Re: Electron Configuration

Just remember to write them in numerical order, this is because of the energy levels.

Nicoli Peiris 1B
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Joined: Wed Sep 30, 2020 10:02 pm

### Re: Electron Configuration

I would go by shell number. So for example 3d10 goes before 4s2.

Gabriel Nitro 1E
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### Re: Electron Configuration

Hi,

Typically, when we are doing electron configurations, we number the electrons in order of lowest energy to highest energy. You can think of it as having the principal quantum number be listed in order of consequence (n=1, 2, 3... => 1s 2s 3s 4s) and in order of the subshells (s then p then d then f).

Hope this helps! :)

Eileen Quach Dis 2A
Posts: 194
Joined: Wed Sep 30, 2020 9:49 pm

### Re: Electron Configuration

The textbook is right.When you write the electron configuration, 3d^10 comes before 4s^2. The reason why Professor Lavelle mentioned that 4s^2 comes before 3d^10 is because that's the order if you read from left to right in the periodic table so people might think that that's the order of the electron configuration. However, when it comes to writing the electron configuration you need to put 3d^10 then 4s^2 since 3d^10 has a lower energy than 4s^2.

reyvalui_3g
Posts: 95
Joined: Wed Sep 30, 2020 9:52 pm

### Re: Electron Configuration

This rule will apply for other orbitals as well. For example, it would be 4d10 5s2 or 5s2 5p6 5d10 5f14 6s2

IshanModiDis2L
Posts: 95
Joined: Wed Sep 30, 2020 9:49 pm

### Re: Electron Configuration

When you are configuring an electron configuration, you would write it in the order of lowest to highest energy level/shell number.

Ansh Patel 2I
Posts: 100
Joined: Wed Sep 30, 2020 9:42 pm

### Re: Electron Configuration

Hi! This conflicts with what most of us learned in high school, but we are supposed to write out the electron configurations in the order of lowest to highest energy levels. So in this case, 3d10 will come before 4s2.

Heather Szeszulski 1I
Posts: 59
Joined: Wed Sep 30, 2020 9:55 pm

### Re: Electron Configuration

Ansh Patel 3I wrote:Hi! This conflicts with what most of us learned in high school, but we are supposed to write out the electron configurations in the order of lowest to highest energy levels. So in this case, 3d10 will come before 4s2.

is there a reason they taught it differently in high school?