Octet Rule exceptions

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Celine 1F
Posts: 98
Joined: Fri Aug 02, 2019 12:16 am

Octet Rule exceptions

Postby Celine 1F » Sun Nov 03, 2019 8:56 pm

How do know which elements don't have to follow the octet rule?

Kevin Antony 2B
Posts: 61
Joined: Sat Sep 07, 2019 12:16 am

Re: Octet Rule exceptions

Postby Kevin Antony 2B » Sun Nov 03, 2019 8:58 pm

H, He, Li, Be, B, and Al I believe will never have a full octet. Additionally, some elements like Si, P, S, and Cl can have expanded octets. I'm pretty sure we just have to memorize what the exceptions are.

Juliet Stephenson 4E
Posts: 85
Joined: Wed Sep 18, 2019 12:21 am

Re: Octet Rule exceptions

Postby Juliet Stephenson 4E » Sun Nov 03, 2019 9:03 pm

Hydrogen, Helium, Lithium, and Beryllium are exceptions because they only have s orbitals. Elements that are period 3+ can also potentially expand their octet.

Juliet Stephenson 4E
Posts: 85
Joined: Wed Sep 18, 2019 12:21 am

Re: Octet Rule exceptions

Postby Juliet Stephenson 4E » Sun Nov 03, 2019 9:05 pm

Kevin Antony 1J wrote:H, He, Li, Be, B, and Al I believe will never have a full octet. Additionally, some elements like Si, P, S, and Cl can have expanded octets. I'm pretty sure we just have to memorize what the exceptions are.

What is the reasoning behind Al not being able to have a full octet?

Deana Moghaddas 3E
Posts: 51
Joined: Fri Aug 30, 2019 12:17 am

Re: Octet Rule exceptions

Postby Deana Moghaddas 3E » Sun Nov 03, 2019 9:06 pm

Elements beyond the 3rd period can potentially break the octet rule

Grecia Velasco 4D
Posts: 56
Joined: Thu Jul 11, 2019 12:17 am

Re: Octet Rule exceptions

Postby Grecia Velasco 4D » Mon Nov 04, 2019 9:30 pm

Juliet Stephenson 4E wrote:Hydrogen, Helium, Lithium, and Beryllium are exceptions because they only have s orbitals. Elements that are period 3+ can also potentially expand their octet.


So any element besides the first 10 elements can have expanded octets?

905416023
Posts: 54
Joined: Thu Jul 25, 2019 12:17 am

Re: Octet Rule exceptions

Postby 905416023 » Mon Nov 04, 2019 9:36 pm

The 3rd period and after I believe it is.

Leila_4G
Posts: 96
Joined: Sat Sep 14, 2019 12:17 am

Re: Octet Rule exceptions

Postby Leila_4G » Tue Nov 05, 2019 12:01 am

Does anyone happen to know a fun/easy limerick to help memorize these?
Thanks!

Minh Ngo 4G
Posts: 109
Joined: Thu Jul 25, 2019 12:17 am

Re: Octet Rule exceptions

Postby Minh Ngo 4G » Tue Nov 05, 2019 1:41 am

Leila_4E wrote:Does anyone happen to know a fun/easy limerick to help memorize these?
Thanks!

I think the trick is your periodic table since you always gonna have it. Period 3+ meaning it n =3, l=0 (s), 1 (p), 2(d). So it has that extra d orbital that it doesn't utilize. Therefore, elements in period 3+ have an expanded octet.

Victoria Otuya 4F
Posts: 50
Joined: Wed Sep 18, 2019 12:21 am

Re: Octet Rule exceptions

Postby Victoria Otuya 4F » Thu Nov 07, 2019 9:05 pm

Why is it that H, He, Li, Be, B, and Al will never be a full octet?

Giselle Littleton 1F
Posts: 58
Joined: Wed Sep 18, 2019 12:20 am

Re: Octet Rule exceptions

Postby Giselle Littleton 1F » Fri Nov 08, 2019 3:10 pm

Some of the elements in the d block have unfilled orbitals. So it depends on the orbital.

ranqiao1e
Posts: 51
Joined: Sat Sep 14, 2019 12:15 am

Re: Octet Rule exceptions

Postby ranqiao1e » Fri Nov 08, 2019 9:56 pm

When making an exception can lower the formal charge or make it a lot more stable.

kendal mccarthy
Posts: 83
Joined: Wed Nov 14, 2018 12:22 am

Re: Octet Rule exceptions

Postby kendal mccarthy » Sun Nov 10, 2019 11:00 pm

Yes some examples are H, He, Li, Be, B, and Al.

005321227
Posts: 87
Joined: Sat Sep 07, 2019 12:15 am

Re: Octet Rule exceptions

Postby 005321227 » Sun Nov 10, 2019 11:07 pm

The first four elements will never have an octet. P,Cl, and S will typically break the octet

Nathan Rothschild_2D
Posts: 106
Joined: Fri Aug 02, 2019 12:15 am

Re: Octet Rule exceptions

Postby Nathan Rothschild_2D » Sun Nov 10, 2019 11:09 pm

Can someone explain why these elements are exceptions?


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