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Topic: HClO4 Best Resonance Structure  (Read 13410 times)

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Offline PopcornMuffin

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HClO4 Best Resonance Structure
« on: December 05, 2007, 12:32:18 AM »
I'm trying to find the resonance structure of HClO4 that contributes most to its true structure.

All four O atoms are bonded to the central chlorine atom and the H atom is bonded to an oxygen atom.
Cl will have a formal charge of zero and an expanded octet.

I can't figure out a way to draw this out. With an expanded octet, I keep giving Cl a formal charge of either +1 or +2.

Offline AWK

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Re: HClO4 Best Resonance Structure
« Reply #1 on: December 05, 2007, 01:27:31 AM »
What do you mean by an expanded octet.
In the case of HCLO4 forget octet rule.
Draw a tentative structure with three doble bonds. Then split the second bond of each double bond separately to form 3 resonance structure with a formal charge +1 on Cl.
Going by the same way split 2 of double bonds. You will gett next three resonance structure with +2 charge on Cl atom.
Finally do the same with all double bond. This will give you one resonance structure with +3 formal charge at Cl.
AWK

Offline agrobert

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Re: HClO4 Best Resonance Structure
« Reply #2 on: December 05, 2007, 03:35:19 PM »
Chlorine has a +7 oxidation state in HClO4.

http://en.wikipedia.org/wiki/Perchlorate
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Offline AWK

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Re: HClO4 Best Resonance Structure
« Reply #3 on: December 06, 2007, 12:59:19 AM »
Chlorine has a +7 oxidation state in HClO4.

http://en.wikipedia.org/wiki/Perchlorate
This is a trivial statement in this discussion.
We discuss here about formal charge of Cl in different resonance structure, not about oxidation number oc chlorine.
A mean structure of chlorate(VII) anion is mean and idealized one and does not give any information on number of possible resonance forms, except that they exists. In my crystallographic experience I did not found such idealized form of chlorate.
AWK

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