Homework Problem 2.39 Issue

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Omer Lavian 2K
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Joined: Wed Sep 21, 2016 2:57 pm

Homework Problem 2.39 Issue

Postby Omer Lavian 2K » Wed Oct 12, 2016 11:50 pm

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

I can't pull up a picture of the diagrams for the problem for some reason, but here are the configurations given, at least based on how I interpreted the diagrams.

(a) C 1s22s22p2
(b) N 1s22s2sp3
(c) Be 1s2s1sp2
(d) O 1s22s22p4

The answer says that all the only ground state configuration here is (d) and all the rest are excited, whereas I answered that (c) is the only excited state and the rest are all ground. What am I missing?

Jose_Arambulo_2I
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Joined: Wed Sep 21, 2016 2:59 pm

Re: Homework Problem 2.39 Issue

Postby Jose_Arambulo_2I » Thu Oct 13, 2016 12:07 am

Good question!
What you forget to consider was the spins and the orbitals used in the diagrams. Oxygen diagram is the only ground state example not only because it has 6 electrons, but also because the electrons are distributed in the most stable manner possible, taking into account hund's rule and the pauli exclusion principle. The others are unstable... in Carbon, the diahram fills the 2px orbital rather than putting another electron of the same spin on the 2py orbital. The Nitrogen cannot be in the ground state because the electron on the 2py orbital is spinning the opposite direction for no reason (opposite spin's only necessary with two electron in the same orbital state. Finally Be isn't in its ground state because instead of filling the 2s orbital with 2 electrons, the diagram puts one electeon in the 2s orbital and the other in the 2p orbital.

Omer Lavian 2K
Posts: 44
Joined: Wed Sep 21, 2016 2:57 pm

Re: Homework Problem 2.39 Issue

Postby Omer Lavian 2K » Thu Oct 13, 2016 1:25 pm

Thank you!

Kayla_Black_2B
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Re: Homework Problem 2.39 Issue

Postby Kayla_Black_2B » Fri Oct 14, 2016 10:42 am

About nitrogen in this problem, I'm curious if it's even possible for one of the unpaired electrons to have an opposite spin to the other two unpaired electrons. Is this a violation of Hund's Rule?

Xiaoman_Kang_2J
Posts: 19
Joined: Wed Sep 21, 2016 3:00 pm

Re: Homework Problem 2.39 Issue

Postby Xiaoman_Kang_2J » Sun Oct 30, 2016 11:21 am

Kayla_Black_3A wrote:About nitrogen in this problem, I'm curious if it's even possible for one of the unpaired electrons to have an opposite spin to the other two unpaired electrons. Is this a violation of Hund's Rule?


Yes, It is possible and that's why this is not a ground state configuration. The opposite spin makes the electron have higher energy.


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