Why is the 4s state filled before the 3d state?

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vuongnaomi1L
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Why is the 4s state filled before the 3d state?

Postby vuongnaomi1L » Sun Nov 01, 2020 11:45 pm

For K (potassium) on the periodic table, after Argon, you would just jump to period 4 for K, which would result in the electron configuration of potassium, K: [Ar]4s^1.

Therefore the energy of the 4s state will be lower than the 3d state unless I fill the 3d state for another element (ie, scandium), which will cause the 3d state to be lower than the 4s state. This true is because electrons fill lower energy orbitals first to represent the ground-state electron configuration.

To my understanding, the reason why I would skip filling the 3d state is because it does not show up on the periodic table in that order? Or is there another explanation of why the 3d state is skipped that is not related to the periodic table placement?

vanessanguyen3I
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Re: Why is the 4s state filled before the 3d state?

Postby vanessanguyen3I » Sun Nov 01, 2020 11:47 pm

I think Dr. Lavelle said that based on experimental data, that's how they determined that Potassium fills its 4s shell first. The periodic table should simply help you remember!

TrishaP_3E
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Re: Why is the 4s state filled before the 3d state?

Postby TrishaP_3E » Mon Nov 02, 2020 3:46 pm

Like you said initially, the 4s orbital has a lower energy than 3d, and because orbitals with the lowest energy are filled first, 4s will be filled before 3d.

SahajDole_1C
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Re: Why is the 4s state filled before the 3d state?

Postby SahajDole_1C » Mon Nov 02, 2020 4:51 pm

The 4s shell has a lower energy level than 3d, which is why the 4s shell fills first

Katie Le 3K
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Re: Why is the 4s state filled before the 3d state?

Postby Katie Le 3K » Tue Nov 03, 2020 6:21 pm

The 4s shell has less energy than 3d so electrons fill the lesser energy shell first.

Sydney Jensen 3L
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Re: Why is the 4s state filled before the 3d state?

Postby Sydney Jensen 3L » Thu Nov 05, 2020 8:19 am

The energy levels that are lowest are the ones that are filled up first, and although 4 is after 3, the s sublevel has a lower energy state than the p sublevel, and when looking at the periodic table, the 3d sublevel is the first d level, which is a larger jump than the 3s to 4s subelevel, meaning it has more energy.

Annette Fishman
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Re: Why is the 4s state filled before the 3d state?

Postby Annette Fishman » Thu Nov 05, 2020 10:25 am

The energy levels that are lowest are filled up first. Based on experimental data, it was found that the 4S shell has less energy than the 3D shell, so that's why it is filled up first.

Jordan_OBrien_2k
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Re: Why is the 4s state filled before the 3d state?

Postby Jordan_OBrien_2k » Thu Nov 05, 2020 11:05 am

The 3d orbitals have a higher energy than the 4s orbitals. Since the 4s orbitals have a lower energy they get filled first in the electron configurations. Then, when the 3d orbitals are filled, 4s isn't lower in energy anymore

CesarLec1
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Re: Why is the 4s state filled before the 3d state?

Postby CesarLec1 » Thu Nov 05, 2020 1:46 pm

So like am I getting this right correct me if I am wrong, initially the 4s orbital is lower in energy than the 3d orbital so it gets filled up first. But once the 3d orbital is half full it becomes lower in energy than the 4s as it takes away an electron from that orbital? then the 3d gets filled up completely and then 4s gets its final electron?

AlyssaMaynard1C
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Re: Why is the 4s state filled before the 3d state?

Postby AlyssaMaynard1C » Thu Nov 05, 2020 1:53 pm

My TA, Andrew Salmon, talked about the orbitals in discussion this week. It's helpful to draw out the chart making columns of 1-7s, then 2-7p, then 3-7d, and finally 4-7f. From there, lightly draw diagonal arrows over 1s, then 2s, then 2p and 3s, then 3p and 4s, then 3d and 4p and 5s, keep repeating until every set has a line through it. This is the order you go in when writing the configurations.

Shana Patel 1C
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Re: Why is the 4s state filled before the 3d state?

Postby Shana Patel 1C » Sat Nov 07, 2020 10:47 pm

AlyssaMaynard1C wrote:My TA, Andrew Salmon, talked about the orbitals in discussion this week. It's helpful to draw out the chart making columns of 1-7s, then 2-7p, then 3-7d, and finally 4-7f. From there, lightly draw diagonal arrows over 1s, then 2s, then 2p and 3s, then 3p and 4s, then 3d and 4p and 5s, keep repeating until every set has a line through it. This is the order you go in when writing the configurations.


This was so helpful. I did not know of this trick before and it makes so much sense.
Also, orbitals with the lowest energy levels get filled the fastest, therefore 4s would be filled before 3d, as 4s has a lower energy level than 3d.

Isabella Cortes 2H
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Re: Why is the 4s state filled before the 3d state?

Postby Isabella Cortes 2H » Sat Nov 07, 2020 11:12 pm

Electrons will fill orbital levels of lowest energy first and 4s has a lower energy than 3d. I also agree with the post above about the chart on how to fill the orbitals, its super helpful!!

Gustavo_Chavez_1K
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Re: Why is the 4s state filled before the 3d state?

Postby Gustavo_Chavez_1K » Sun Nov 08, 2020 10:21 am

Yeah so to conserve energy, electrons will fill orbital levels that with the lowest energy levels. This is why 4s is filled before 3d.

AlyssaMaynard1C
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Re: Why is the 4s state filled before the 3d state?

Postby AlyssaMaynard1C » Sun Nov 08, 2020 1:16 pm

Shana Patel 1C wrote:
AlyssaMaynard1C wrote:My TA, Andrew Salmon, talked about the orbitals in discussion this week. It's helpful to draw out the chart making columns of 1-7s, then 2-7p, then 3-7d, and finally 4-7f. From there, lightly draw diagonal arrows over 1s, then 2s, then 2p and 3s, then 3p and 4s, then 3d and 4p and 5s, keep repeating until every set has a line through it. This is the order you go in when writing the configurations.


This was so helpful. I did not know of this trick before and it makes so much sense.
Also, orbitals with the lowest energy levels get filled the fastest, therefore 4s would be filled before 3d, as 4s has a lower energy level than 3d.

I'm so glad it helped! As soon as he explained it with the chart, everything really clicked. It might be helpful to draw it out and put it in your notes to reference easily!

Kandyce Lance 3E
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Re: Why is the 4s state filled before the 3d state?

Postby Kandyce Lance 3E » Sun Nov 08, 2020 6:00 pm

SahajDole_1G wrote:The 4s shell has a lower energy level than 3d, which is why the 4s shell fills first



So basically, the takeaway from this question is that it doesn't necessarily matter the number being filled in the shell but the energy level?


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