Formal charge on atom w/ expanded valence shell


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Daniela Alvarado 3B
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Joined: Thu Sep 27, 2018 11:26 pm

Formal charge on atom w/ expanded valence shell

Postby Daniela Alvarado 3B » Sat Nov 24, 2018 7:29 pm

If we have for example XeF4 (ch. 3.65 6th ed), the formal charge on Xe is zero; however, when we’re looking at the bond pairs and lone pairs there’s 12 electrons around the Xe. Will the charge for atoms w expanded valence shells always be 0?

Elaine Pham 2E
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Joined: Thu Sep 27, 2018 11:28 pm
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Re: Formal charge on atom w/ expanded valence shell

Postby Elaine Pham 2E » Sun Nov 25, 2018 11:34 am

Usually, I think that the purpose of the expanded valence shell is to get the formal charge of the central atom to be neutral. But I'm not sure if it's necessarily that all atoms with an expanded octet when bonded to other atoms will have a formal charge of 0. When you're looking at XeF4 particularly, there's still technically 8 valence electrons around Xe (which fulfills its octet and allows for the formal charge of 0), not 12 because when counting formal charge you count electrons in the bond as 1 not 2. So with 4 bonds and 4 extra electrons in lone pairs, there is 8 valence electrons and so formal charge is 0 for Xe.


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