## Octet Expansion and d-Orbitals

$sp, sp^{2}, sp^{3}, dsp^{3}, d^{2}sp^{3}$

Dayna Pham 1I
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### Octet Expansion and d-Orbitals

With regards to the dsp3 hybridized orbitals as well as the d2sp3 hybridized orbitals, octet expansion involves the d-orbitals, which starts at phosphorus. Why does octet expansion begin at phosphorus? I thought anything in the third row could have an expanded octet; why not Aluminum or Silicon?

Thanks!

Sarah Fatkin 4I
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Joined: Fri Sep 28, 2018 12:27 am

### Re: Octet Expansion and d-Orbitals

Hi Danya! You're right about elements with n=3 or higher can have an expanded octet because they have access to the d-orbital. I'm pretty sure that Silicon can have an expanded octet. As for Aluminum, while it can have an expanded octet, it often has a sextet. For example, Aluminum has a sextet in Aluminum trichloride.

Nicolette_Canlian_2L
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### Re: Octet Expansion and d-Orbitals

So is any element in the first 3 groups without a d-orbital in its shell unable to fulfill the octet rule?

Dayna Pham 1I
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### Re: Octet Expansion and d-Orbitals

Nicolette_Canlian_3G wrote:So is any element in the first 3 groups without a d-orbital in its shell unable to fulfill the octet rule?

Under my current understanding, I believe any element in the first three groups don't have to meet the octet rule of maximum 8 electrons, it can exceed the octet rule since it has access to the d orbitals.

Nicolette_Canlian_2L
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### Re: Octet Expansion and d-Orbitals

Dayna Pham 1G wrote:
Nicolette_Canlian_3G wrote:So is any element in the first 3 groups without a d-orbital in its shell unable to fulfill the octet rule?

Under my current understanding, I believe any element in the first three groups don't have to meet the octet rule of maximum 8 electrons, it can exceed the octet rule since it has access to the d orbitals.

How can it exceed the octet rule? Sorry I'm a bit unclear on that.

Nancy Hu - 4E
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Joined: Fri Sep 28, 2018 12:28 am

### Re: Octet Expansion and d-Orbitals

Nicolette_Canlian_3G wrote:
Dayna Pham 1G wrote:
Nicolette_Canlian_3G wrote:So is any element in the first 3 groups without a d-orbital in its shell unable to fulfill the octet rule?

Under my current understanding, I believe any element in the first three groups don't have to meet the octet rule of maximum 8 electrons, it can exceed the octet rule since it has access to the d orbitals.

How can it exceed the octet rule? Sorry I'm a bit unclear on that.

I thought that the first two periods are unable to to break the octet rule since they don't have access to the d orbital but the 3rd period and below can.

Katelyn Phan 2A
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Joined: Fri Sep 28, 2018 12:23 am

### Re: Octet Expansion and d-Orbitals

Nicolette_Canlian_3G wrote:
Dayna Pham 1G wrote:
Nicolette_Canlian_3G wrote:So is any element in the first 3 groups without a d-orbital in its shell unable to fulfill the octet rule?

Under my current understanding, I believe any element in the first three groups don't have to meet the octet rule of maximum 8 electrons, it can exceed the octet rule since it has access to the d orbitals.

How can it exceed the octet rule? Sorry I'm a bit unclear on that.

It's able to expand beyond the octet rule because from period 3, we are going into p-orbitals that have px, py, and pz.

Carolina Lechuga
Posts: 33
Joined: Fri Sep 28, 2018 12:17 am

### Re: Octet Expansion and d-Orbitals

Aren't there some elements in the third row and below that can't have an octet expansion due to an exception? Im really confused on those

Carolina Lechuga
Posts: 33
Joined: Fri Sep 28, 2018 12:17 am

### Re: Octet Expansion and d-Orbitals

Aren't there some elements in the third row and below that can't have an octet expansion due to an exception? Im really confused on those