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For example, oxygen is neutral when it has just 6 electrons. But the pink O in the molecule pictured has 3 bonds giving it 8 electrons, a full-octet. It's more electronegative than all the atoms it's bonded to also. It would make sense if an O with a full-octet had a -2 charge since it has an extra 2 electrons.

But because it "owns" only 1 electron from each bond, the O has a positive charge. This doesn't make sense to me: if we don't count the extra electrons in its charge, why do we count them towards its octet? C2OH

  • Where do the bonding electrons come from? This question might help. – Safdar Faisal Sep 20 '20 at 05:13
  • Umm, such issue winding up in sugar hydrolysis of all things is rather surprising... – Mithoron Sep 20 '20 at 17:19
  • https://chemistry.stackexchange.com/questions/14478/the-definition-of-formal-charge – Mithoron Sep 20 '20 at 17:21
  • That charge labelled on oxygen atom is formal charge, right? – TheLearner Sep 21 '20 at 04:42
  • @Tge99sLearner No it is a real charge, which can lead to the confusion. – Alchimista Sep 21 '20 at 10:42
  • Your nick fits well with the colourful sugar :) – Alchimista Sep 21 '20 at 10:44
  • I learned that formal charge is actual charge... do both electrons in a bond count towards an atom's charge, or only the one it owns? – histrionics Sep 22 '20 at 02:00
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    @histrionics no it's not. A formal charge is of course formal. The oxygen in your sketch has a real charge. Or the ensemble. But there is a charge somewhere. And it is more around that oxygen. – Alchimista Sep 22 '20 at 18:36
  • Alright thank you. How do I reopen this question? The linked question does not address my question about octets (which are used to tell whether the last shell is full). Both formal charge and oxidation state are contradicted by how we count an atom's electrons in an octet. That is what my question is about. – histrionics Sep 22 '20 at 20:28
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    @Mithoron I vote to reopen the question. The edited question asks about the difference in counting electrons when looking for octets as opposed to assigning formal charges. The linked question compares counting electrons for assigning oxidation states or formal charges. Ideally, there would be a question comparing all three ways of counting to direct all further questions there. – Karsten Sep 22 '20 at 21:52

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