Atomic structure: Chlorine, Aufbau principle Watch

Amphiprion
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I am teaching myself AS and A2 chem from scratch for the first time in 7 years. A bit confused regarding atomic structure, specifically electron filling of energy levels and the illustration (Picture took 2 seconds on paint excuse quality).


All the images of Chlorine atoms I found online have distributed electrons as follows:

1st energy level: 2 e-
2nd energy level: 8 e-
3rd energy level: 7 e-

When considering the Aufbau principle, should this not be 2, 8, 6, 1 (occupying 4 energy levels, not 3).



My reason for thinking this is the skipping of filling d orbitals until after the S orbital of the next energy level. In the image above occupied orbitals are: 1S2, 2S2, 2P6, 3S2, 3P6, 4S1

The final electron occupying orbital 4S because 4S posseses lower energy than the 3D orbitals. However, all the images online seem to suggest it just goes ahead and occupies the first 3D orbital meaning 7 electrons on the 3rd energy level, none occupying the 4th.

I was assuming that is just a simplified method of illustrating the atom for lower levels like GCSE but realised Chlorine is found in group 7 and period 3 on the periodic table which also suggests 3 energy levels with 7 electrons occupying the highest energy level.
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Farseer
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(Original post by Amphiprion)
When considering the Aufbau principle, should this not be 2, 8, 6, 1 (occupying 4 energy levels, not 3).
17 electrons

My reason for thinking this is the skipping of filling d orbitals until after the S orbital of the next energy level. In the image above occupied orbitals are: 1S2, 2S2, 2P6, 3S2, 3P6, 4S1
19 electrons
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Tytrox
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If you look at a periodic table, then Cl has a atomic number of 17, so it has 17 electrons, occupying 1s2, 2s2, 2p6, 3s2, 3p5. Therefore the simper version on the internet is correct
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Amphiprion
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(Original post by Farseer)
17 electrons



19 electrons
Face. ****ing. Palm.

How I managed that I do not know.
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Pigster
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At least you didn't waste more than two seconds doing your paint jobs.
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