Octet Rule  [ENDORSED]

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Amoreno Section 1E
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Octet Rule

Postby Amoreno Section 1E » Sat Jul 15, 2017 3:47 pm

What are the exceptions in the octet rule?

Dabin Kang 1B
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Re: Octet Rule

Postby Dabin Kang 1B » Sat Jul 15, 2017 3:58 pm

One exception to the octet rule would be when atoms exceed their octet. Starting from phosphorus in period 3, atoms can utilize their d subshell in bonding.

Paul Wong1B
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Re: Octet Rule

Postby Paul Wong1B » Sun Jul 16, 2017 8:10 am

Another exception would be when when an atom has too little electrons in a compound. BeCl2, for example, is a compound in which the central atom does not possess an octet.

Amy Wu 1D
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Re: Octet Rule

Postby Amy Wu 1D » Sun Jul 16, 2017 12:43 pm

Do we have these exceptions to the octet rule only when we are more concerned with formal charge?

Jordan Larrea 1E
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Re: Octet Rule

Postby Jordan Larrea 1E » Sun Jul 16, 2017 9:58 pm

Amy Wu 1D wrote:Do we have these exceptions to the octet rule only when we are more concerned with formal charge?


These exceptions have more to do with the fact that the d orbital is available, so it is used. Recall that the transition metals have a configuration one less than the row they're in, meaning that the metals in the n=4 row have the configuration of 3d. Because the 3d orbital exists in the third row, P, S, and Cl can use it. It's more to do with, it's there so we'll use it.

Amy Wu 1D
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Re: Octet Rule

Postby Amy Wu 1D » Sun Jul 30, 2017 3:19 pm

Jordan Larrea 1E wrote:
Amy Wu 1D wrote:Do we have these exceptions to the octet rule only when we are more concerned with formal charge?


These exceptions have more to do with the fact that the d orbital is available, so it is used. Recall that the transition metals have a configuration one less than the row they're in, meaning that the metals in the n=4 row have the configuration of 3d. Because the 3d orbital exists in the third row, P, S, and Cl can use it. It's more to do with, it's there so we'll use it.

Ah, okay. Thank you for the clear explanation!

404995677
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Re: Octet Rule

Postby 404995677 » Fri Oct 27, 2017 3:34 pm

Hi I am still a little confused. So do the electrons go to to the 3d orbital for P, S, and Cl?

605011646
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Re: Octet Rule

Postby 605011646 » Fri Oct 27, 2017 5:13 pm

no, it only goes to 3p

Ethan Mondell 1A
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Re: Octet Rule

Postby Ethan Mondell 1A » Fri Oct 27, 2017 8:15 pm

Another exception to the octet rule would be radicals, compounds with unpaired electrons, meaning they would always have an odd number of electrons. Radicals, for the most part, are very temporary molecules and usually only form temporarily in some reactions.

Chem_Mod
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Re: Octet Rule  [ENDORSED]

Postby Chem_Mod » Fri Oct 27, 2017 9:17 pm

Hey Everybody!
Great discussion on octets! There was a lot of stuff said in this thread so I'll summarize it and give some clarifications.
First, don't worry about radicals for now. Radicals will be discussed a lot more in later 14 series classes.
Second, exceptions to the octet rule can arise from your desire to minimize the number of atoms with formal charges (such as in the Lewis structure of ClO4-); however, exceptions to the octet rule don't ONLY arise from formal charge concerns.

These are the main exceptions to the octet rule:
-H and He only need to share 2 valence electrons to have a full octet.
-In certain compounds, such as BeCl2, Be only needs to share 4 valence electrons.
-In certain compounds involving the Boron group elements, such as BH3 and AlCl3, the central atom only needs to share 6 valence electrons.
-Typically, elements that are in the 3rd row or lower rows of the periodic table can have expanded octets. For example, in XeF4, Xe shares 12 valence electrons and in SF6, S shares 12 valence electrons.
Hope this helps guys! :D


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