## writing electron configurations

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Fdonovan 3D
Posts: 101
Joined: Sat Aug 17, 2019 12:16 am

### writing electron configurations

I never did electron configurations in high school and I am super lost. In my notes I have that for carbon when there are 6 electrons, the configuration is 1s² 2s² 2px 2py. Could someone please explain to me where these numbers came from?

KHowe_1D
Posts: 103
Joined: Thu Jul 25, 2019 12:15 am
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### Re: writing electron configurations

There are two electron in the first s shell so you have 1s^2

In the second s shell you also have 2 electrons so you have 2s^2

The p shell can hold 6 electrons in its 3 orbitals but since carbon only has 6 total electrons there is one in 2px and one in 2py.
The x and the y indicate which orbitals are filled.

the numbers in front of the shell 1s or 2s just indicate 1st shell and 2nd shell.

So you have 1s^2 2s^2 2px 2py for a total of 6 electrons.

Hope this helps :)

KarineKim2L
Posts: 100
Joined: Fri Aug 30, 2019 12:16 am

### Re: writing electron configurations

To do electron configuration, you look at the periodic table. The first row corresponds with the n=1 level, and the second row corresponds with the n=2 level. Basically, in each row, the 2 elements on the far left are the s1 and s2, while the 6 elements on the far right are the p1,p2,p3,p4,p5,p6. So, Carbon is in the second row, 4 elements over. Thus the electron configuration would be 1s2,2s2,2p2 to account for the 2 elements in the first row, the 2 leftmost elements in the second row, and the 2 elements on the right side of the second row. The px and py are simply orientations of the p orbital. This method just looks at the periodic table, but it would be good to understand why we end up creating the electron configuration in this way.
Last edited by KarineKim2L on Sun Oct 20, 2019 12:57 pm, edited 1 time in total.

Sidharth D 1E
Posts: 98
Joined: Sat Aug 24, 2019 12:17 am

### Re: writing electron configurations

So, what 1s2 2s2 2px 2py, means, is that carbon has 6 electrons, and it occupies these locations. First, there are 2 electrons located in the 1s orbital (which if you are following the periodic table follow the spots of Hydrogen and Helium). Next, there are another 2 electrons located in the 2s orbital (which follow the spots of Lithium and Beryllium). Now, the next "block" where electrons can be located is the 2p subshell. There are a total of 6 spots for electrons in this location, but carbon only has 2 more electrons that would fit in this spot. Now, because of Hund's rule (due to e- repulsion, e- in the same subshell occupy different orbitals with parallel spin/lowest energy), the 2 electrons would be in two separate orbitals with parallel spin, which is 2px and 2py.

simmoneokamoto3K
Posts: 50
Joined: Mon Jun 17, 2019 7:22 am

### Re: writing electron configurations

Fdonovan 3D wrote:I never did electron configurations in high school and I am super lost. In my notes I have that for carbon when there are 6 electrons, the configuration is 1s² 2s² 2px 2py. Could someone please explain to me where these numbers came from?

To add to what the people are saying above, when I was initially learning I used this youtube link which helped me understand electron configuration easier. Hope this helps!

https://www.youtube.com/watch?v=2AFPfg0Como&t=3s

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