## Electron configuration

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

Abigail Menchaca_1H
Posts: 104
Joined: Sat Sep 07, 2019 12:19 am

### Electron configuration

Does anyone know the factual reasoning behind why we fill up the 4s orbital before the 3d orbital?

Posts: 53
Joined: Wed Sep 11, 2019 12:17 am

### Re: Electron configuration

the 4s orbital is lower in energy, so the electrons would rather be there because it is more stable.

Anisha Chandra 1K
Posts: 118
Joined: Thu Jul 11, 2019 12:17 am

### Re: Electron configuration

Yes, the 4s orbital is lower energy than 3d, but once 4s is filled, it becomes higher energy than 3d, which is why electrons will be removed from 4s before 3d during ionization.

Katie Bart 1I
Posts: 104
Joined: Sat Aug 24, 2019 12:16 am

### Re: Electron configuration

Before electrons begin to fill the shells, the 4s orbital is lower in energy than the 3d orbital. However, once the 4s orbital is full and there is at least one electron in the 3d orbital, it becomes lower in energy than 4s, so you write 3d before 4s in the configuration.

Megan_1F
Posts: 49
Joined: Thu Jul 25, 2019 12:16 am

### Re: Electron configuration

It is important to note that the sugbshells increase in energy going from s<p<d<f.

Mariah
Posts: 104
Joined: Fri Aug 02, 2019 12:16 am

### Re: Electron configuration

Anisha Chandra 4H wrote:Yes, the 4s orbital is lower energy than 3d, but once 4s is filled, it becomes higher energy than 3d, which is why electrons will be removed from 4s before 3d during ionization.

So to clarify, if we need to remove electrons we would go to 4s before 3d, because this confused me.

Anisha Chandra 1K
Posts: 118
Joined: Thu Jul 11, 2019 12:17 am

### Re: Electron configuration

Mariah wrote:
Anisha Chandra 4H wrote:Yes, the 4s orbital is lower energy than 3d, but once 4s is filled, it becomes higher energy than 3d, which is why electrons will be removed from 4s before 3d during ionization.

So to clarify, if we need to remove electrons we would go to 4s before 3d, because this confused me.

Yes, that is correct.

Catherine Daye 1L
Posts: 104
Joined: Wed Sep 11, 2019 12:16 am

### Re: Electron configuration

The 4s orbital is lower in energy. However, when it is full, it becomes higher in energy than 3d. This explains why we write electron configurations like 3d^2 4s^2 4p^6.