4s and 3d

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JTieu_1L
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4s and 3d

Postby JTieu_1L » Mon Oct 26, 2020 4:31 pm

What is the reason for why 3d goes before 4s other than the fact from how it is arranged in the periodic table?

Tam Nguyen 2B
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Re: 4s and 3d

Postby Tam Nguyen 2B » Mon Oct 26, 2020 4:48 pm

I think it's because the electrons have to fill in all of the spaces of the 3d orbital before they can move on to the 4s orbital. The 4s orbital is in the next energy level.

Thomas Vu 1A
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Re: 4s and 3d

Postby Thomas Vu 1A » Wed Oct 28, 2020 10:24 pm

Just to add on to what was said, the main exception that we have to worry about, based on what Dr. Lavelle said in his lecture, is Scandium which can be written as [Ar]3d1 4s2

Navdha Sharma 3J
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Re: 4s and 3d

Postby Navdha Sharma 3J » Wed Oct 28, 2020 10:27 pm

I think that's because of the Aufbau principle which states that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels.
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Astha Sahoo 3I
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Re: 4s and 3d

Postby Astha Sahoo 3I » Thu Oct 29, 2020 12:12 am

You would need to fill the 3rd shell before going onto the fourth one. An electron would be pulled into the 3rd subshell if there was space in the 3rd subshell. Electrons are pulled towards the nucleus due to effective nuclear charge, so if there is a space in the 3rd subshell, an electron will move there from the 4th subshell.

Kyle Dizon 3A
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Re: 4s and 3d

Postby Kyle Dizon 3A » Thu Oct 29, 2020 7:42 am

I believe the 3d would have to be filled up by an electron to its full capacity in order for the electron to go to the next energy level.

Lorraine Jiang 2C
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Re: 4s and 3d

Postby Lorraine Jiang 2C » Thu Oct 29, 2020 9:31 am

Hi! In general terms, the electrons have to fill up the 3d orbital first before they move on to the 4s orbital because it is at a lower energy state. But there are two exceptions, Potassium and Calcium, which fills the 4s orbital first.

Hope it helps!

Chudi Onyedika 3A
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Re: 4s and 3d

Postby Chudi Onyedika 3A » Sat Oct 31, 2020 1:46 pm

The 3d orbital must be filled prior to entering the 4s orbital.

Chinyere Okeke 2J
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Re: 4s and 3d

Postby Chinyere Okeke 2J » Sat Oct 31, 2020 5:15 pm

It goes that way because usually 3d orbital is lower energy than 4s orbital with the exception of certain elements like Ca and K. This is because an e- in the 3d orbital will have lower energy than 4s, only after the 4s orbital is occupied.

Jeremy Wei 2C
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Re: 4s and 3d

Postby Jeremy Wei 2C » Sat Oct 31, 2020 8:44 pm

Hi, so in this case 3d comes first because the 3d orbital has lower energy when compared to the 4s orbital. Hope this helps! This is one of the main exceptions talked about because it seems out of order.

Carly_Lipschitz_3H
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Re: 4s and 3d

Postby Carly_Lipschitz_3H » Sun Nov 01, 2020 6:49 pm

The 3d orbital has to be filled up first because it is a lower energy level than 4s. You always have to fill up the energy levels in order. Hope this helps.

Joshua Chung 2D
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Re: 4s and 3d

Postby Joshua Chung 2D » Sun Nov 01, 2020 6:54 pm

The third is written before the fourth simply because it notates a lower n-value (shell). Since these are written in ascending order by convention, 3d will always come before 4s.

Joshua Chung 2D
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Re: 4s and 3d

Postby Joshua Chung 2D » Sun Nov 01, 2020 6:54 pm

The third is written before the fourth simply because it notates a lower n-value (shell). Since these are written in ascending order by convention, 3d will always come before 4s.

Keshav Patel 14B 2B
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Re: 4s and 3d

Postby Keshav Patel 14B 2B » Sun Nov 01, 2020 6:59 pm

Always remember except for rare cases that electrons will always fill lower levels before they move onto higher levels. 4s is a higher energy level than 3d, hence the reason 3d fills first.

Ayesha Aslam-Mir 3C
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Re: 4s and 3d

Postby Ayesha Aslam-Mir 3C » Sun Nov 01, 2020 8:33 pm

Quick question: why do electrons in the s orbital have a lower energy than p electrons ? It is just due to theshape of the orbital? And how are different orbitals grouped into the same energy level if some have lower or higher energy than others? (My only understanding in the exception for Cr and Mn is the sake of symmetry in the energy level)-- can anyone clear up this concept?


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