List of octect exceptions

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Hannah Pham 1D
Posts: 62
Joined: Fri Sep 28, 2018 12:19 am

List of octect exceptions

Postby Hannah Pham 1D » Wed Nov 07, 2018 3:04 pm

Can someone provide a brief, undetailed list of the octet exceptions we have learned so far?

Austin Clack
Posts: 29
Joined: Fri Sep 28, 2018 12:17 am

Re: List of octect exceptions

Postby Austin Clack » Wed Nov 07, 2018 4:26 pm

There are three specific exceptions I believe we've covered so far.

1) molecules, like NO, with an odd number of electrons
2) molecules in which one or more atoms possess more than eight electrons, such as SF6
3) molecules such as BCl3, in which one or more atoms possess less than eight electrons.

I know it can be confusing to keep track of these, but. just remember before drawing a Lewis structure to always count your electrons to avoid any issues.

Kyle Golden Dis 2G
Posts: 67
Joined: Fri Sep 28, 2018 12:17 am

Re: List of octect exceptions

Postby Kyle Golden Dis 2G » Wed Nov 07, 2018 4:29 pm

The first four elements (H, He, Li, Be) are exceptions along with radicals and elements in the third period and below.

Francis_Nguyen3D
Posts: 35
Joined: Fri Sep 28, 2018 12:24 am

Re: List of octect exceptions

Postby Francis_Nguyen3D » Wed Nov 07, 2018 4:36 pm

I believe the exceptions we have learned so far consists of:
1. Electron deficiency- which is when there is less than an octet, therefore causing a fourth bond to be made. For example: BF3, since Boron is short one bond to complete its octet, it would seek out another F atom to form BF4-.This would allow it to become more stable.
2. Expanded Octet- Elements in period 3 and greater are able to expand their octet. This allows the molecule to accommodate more than 8 electrons.
3. Radicals- This is when a molecule has an uneven number of valence electrons which causes one electron to be unpaired. Ex. NO2
4. First four elements

Shreya Tamatam 3B
Posts: 30
Joined: Fri Sep 28, 2018 12:25 am

Re: List of octect exceptions

Postby Shreya Tamatam 3B » Thu Nov 08, 2018 11:37 pm

Does anyone know why H, He, Li, and Be are octet exceptions? What is the explanation behind why they don't conform to the octet rule?

Angel Chen 2k
Posts: 59
Joined: Fri Sep 28, 2018 12:20 am

Re: List of octect exceptions

Postby Angel Chen 2k » Sun Nov 11, 2018 11:22 pm

For the first row, the ground state form of He is a duet instead of the octet. It is the most stable form for the atoms of the first several elements.
For the first two rows, we do not normally exceed the duet or the octet.
For the atoms the elements below, sometimes they can exceed the octet.

Hope this helps!

Shibhon_Shepard
Posts: 62
Joined: Wed Nov 15, 2017 3:04 am

Re: List of octect exceptions

Postby Shibhon_Shepard » Tue Nov 13, 2018 5:16 pm

For these exceptions are we able to draw a Lewis structure for them? (if any)


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