Beryllium Octet Rule

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Cristian Carrasco 1F
Posts: 52
Joined: Fri Sep 29, 2017 7:06 am

Beryllium Octet Rule

Postby Cristian Carrasco 1F » Tue Nov 07, 2017 8:22 pm

Can someone please explain why beryllium does not follow the octet rule in some cases like BeCl2???

Harrison Wang 1H
Posts: 50
Joined: Fri Sep 29, 2017 7:07 am

Re: Beryllium Octet Rule

Postby Harrison Wang 1H » Tue Nov 07, 2017 9:09 pm

The first four elements of the periodic table up to boron never obtain an octet of electrons

dstemp
Posts: 20
Joined: Fri Sep 29, 2017 7:07 am

Re: Beryllium Octet Rule

Postby dstemp » Tue Nov 07, 2017 9:28 pm

Then why does Boron in BF3 not have a full octet either?

Clara Hu 1G
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Re: Beryllium Octet Rule

Postby Clara Hu 1G » Wed Nov 08, 2017 12:44 pm

The Boron in BF3 does not have a full octet because BF3 is a Lewis Acid, and the empty p-orbital on B can accept an electron lone pair from a Lewis Base.

Sarah Rutzick 1L
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Joined: Tue Oct 10, 2017 7:13 am

Re: Beryllium Octet Rule

Postby Sarah Rutzick 1L » Wed Nov 08, 2017 3:37 pm

To add to this, you can tell that beryllium will now have a full octet because of formal charge. In BeCl2, Be has 2 shared bonds, making its formal charge 0, and Cl has 6 unshared electrons and 1 shared bond, making the formal charge of both Cl atoms in BeCl2 0. This proves to be the most stable structure for BeCl2.

Humza_Khan_2J
Posts: 56
Joined: Thu Jul 13, 2017 3:00 am

Re: Beryllium Octet Rule

Postby Humza_Khan_2J » Sat Nov 11, 2017 5:49 pm

Is the reason Be doesn't need an octet because of the amount of valence electrons it has?

Curtis Wong 2D
Posts: 62
Joined: Sat Jul 22, 2017 3:00 am

Re: Beryllium Octet Rule

Postby Curtis Wong 2D » Sat Nov 11, 2017 6:01 pm

Beryllium doesn't fulfill the octet rules because of its valence electrons and the orbitals they occupy. Just like H, He, Li, and Be, they are all exceptions to the octet rules mainly because they don't need 8 to feel complete. Their s-orbitals do not need 8 electrons to complete the shell to feel full, so they don't follow the octet rule.

Boron is a weird exception. Boron and Aluminum (as well as some other group 13 compounds) do not require an octet as well in their compounds. The textbook was not clear on why this occurred in group 13 compounds, but they said that they may have an incomplete octet, or require a halogen atom to act as bridge to give them more.


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