Octet Exception

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Matia Kim 1B
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Joined: Fri Apr 06, 2018 11:03 am

Octet Exception

Postby Matia Kim 1B » Sun May 20, 2018 11:41 pm

How do you know if a bond will have an octet exception or not? Is it only by memorization or position of an element on the periodic table?

Posts: 62
Joined: Fri Apr 06, 2018 11:04 am

Re: Octet Exception

Postby danielruiz1G » Sun May 20, 2018 11:47 pm

I think we just have to memorize the certain ones but what makes them exceptions are if certain molecules have an odd number of electrons, if one of the atoms in the molecules has more than eight electrons, or if one atom has less than eight electrons

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Joined: Fri Apr 06, 2018 11:02 am

Re: Octet Exception

Postby april_bussey_1C » Sun May 20, 2018 11:48 pm

Exceptions to the octet rule fall into one of three categories: (1) an incomplete octet, (2) odd-electron molecules, and (3) an expanded octet.

Gabi Landes 1-H
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Joined: Thu Feb 22, 2018 3:00 am

Re: Octet Exception

Postby Gabi Landes 1-H » Mon May 21, 2018 12:01 am

odd-electron molecules
molecules with an odd number of electrons (e.g., NO).

Electron-deficient molecules
molecules in which atoms have fewer than 8 electrons (e.g., boron chloride and lighter s- and p- block elements )
ie. Hydrogen, Beryllium, and Boron = too few electrons to form octet
----> Hydrogen = 1 valence e-
----> Beryllium = 2 valence e-
----> Boron has = 3 valence e-

expanded valence shell molecules
molecules in which atoms have more than 8 electrons (.e.g, sulfur hexafluoride and elements beyond period 3)

see: https://courses.lumenlearning.com/trident-boundless-chemistry/chapter/exceptions-to-the-octet-rule/

Daniel Cho Section 1H
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Joined: Fri Jun 23, 2017 11:40 am

Re: Octet Exception

Postby Daniel Cho Section 1H » Tue May 22, 2018 1:32 pm

The main thing to understanding expanded octet is that it only works for elements in the 3p orbitals and below mainly because of the d orbitals which is not filled which acts another placeholder for the electrons to fill in the d orbital.

I hope this helps as a way to understanding the expanded octet. The other people have answered to the other exceptions. Please correct me if I am wrong in my explanation.

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Re: Octet Exception

Postby QuincyH1G » Sun May 27, 2018 6:09 pm

So expanded octet doesn't occur in anything past 3p?

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Re: Octet Exception

Postby juliaschreib1A » Sun May 27, 2018 7:29 pm

The exceptions are H, He, Li, Be, S, and F

Yitzchak Jacobson 1F
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Joined: Wed Nov 22, 2017 3:00 am

Re: Octet Exception

Postby Yitzchak Jacobson 1F » Sun May 27, 2018 11:29 pm

Hello, how are you?
To answer your question, to understand which elements have an incomplete octet, there is an option to memorize them. Another way is to memorize that period 3 on the periodic table have an octet exception rule.

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