## Chapter 2 HW: #39 [ENDORSED]

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### Chapter 2 HW: #39

Determine whether each of the following electron configurations represents the ground state or an excited state of the atom given.

Thank you!
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Sylvia_Cai_3D
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### Re: Chapter 2 HW: #39

The answer is (d). The question is asking which electron configuration correctly corresponds to the element next to it. (a) is wrong because of Hund's Rule; due to e- repulsion, the e- should occupy different orbitals first. (b) is wrong because in each orbital, the up arrow spin should go in first before a down arrow spin. (c) is wrong because in the 2s orbital, it is missing a parallel spin to the up arrow. And finally, (d) is correct because the configuration correctly correlates with Hund's Rule and Pauli Exclusion Principle with the correct number of electrons.

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### Re: Chapter 2 HW: #39

I understand why a) b) and c) are all wrong, but I'm confused about why the question asked if the configuration represents the ground state or the excited state when a) b) and c) don't follow Hund's rule?

Sarah_Heesacker_3B
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### Re: Chapter 2 HW: #39

I was confused about that at first as well, but I think that they must follow Hund's Rule to be in the ground state. Since a, b, and c don't follow Hund's Rule, they are in the excited state. Applying Hund's Rule gives the lowest energy electron configuration, which is the ground state, so the ones that don't follow Hund's Rule are in a higher energy state and are therefore excited. I hope that makes sense!

Chem_Mod
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### Re: Chapter 2 HW: #39  [ENDORSED]

Karla_Coronado_1H wrote:Determine whether each of the following electron configurations represents the ground state or an excited state of the atom given.

Thank you!

Hi there!

Let's take another slow read of the question "Determine whether each of the following electron configurations represents the ground state or an excited state of the atom given.

This is not a multiple choice question... but the thought process used here is on the right track! In analyzing each of these configurations we should employ the aufbau principle, Hund's rule, and the Pauli's exclusion principle. In this circumstance, if the shown electron configuration violates any of these rules, then we know that it is in an excited state! (It is not technically an incorrect configuration, it is precisely an incorrect ground state configuration.

(a) excited state
(b) excited state
(c) excited state
(d) ground state

Hope this helps!

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### Re: Chapter 2 HW: #39

Thank you to everyone who replied. This cleared things up.

RubyLake1F
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### Re: Chapter 2 HW: #39

Why is it that b) violates ground state expectations? Isn't it somewhat random whether an electron is spinning up or down at any given moment, so it should not necessarily be true that all of the three electrons in the p orbitals have to be spinning up?

Bianca Nguyen 1B
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### Re: Chapter 2 HW: #39

B) violates ground state expectations because of Hund’s rule. You must fill up electrons parallel to each other first (All up or all down first) because of electron repulsion, but I’m not completely sure what electron repulsion has to do with them all having to be parallel since they’re in different orbitals

haley f
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### Re: Chapter 2 HW: #39

Karla_Coronado_1J wrote:Determine whether each of the following electron configurations represents the ground state or an excited state of the atom given.