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I see you have been editing for a couple of months already, but I thought I would welcome you anyway and say thank you for the improvements you are making to chemistry articles. If you are interested, there is a community of chemists here at Misplaced Pages:WikiProject Chemistry, if you haven't see it already. -- Ed (Edgar181) 13:52, 27 April 2011 (UTC)

Thank you for your welcome. Nao1958 (talk) 06:23, 5 May 2011 (UTC)

SO₂

Just curious, what was the problem with the resonance structures?--Smokefoot (talk) 00:33, 11 May 2011 (UTC)

Please look at the image.

I think the two of the sides are correct. The center has the problem. Now, the right oxygen is O₁ and the left one is O₂. On the left structure, S has one lone pair and O₁ has three lone pairs. When the lonepair of S moves to between S and O₁, the double bond is formed like the center image. However, the number of valence electrons of O₁ is 10. That is against the octet rule. Therefore, the image is incorrect. --Nao1958 (talk) 10:09, 11 May 2011 (UTC)

See File:Sulfur-dioxide-ve-resonance-2D.png for a drawing of what's being discussed here. O=S=O has 10 electrons round sulfur, not oxygen. Oxygen always has 8 electrons round it, in all of these resonance structures. See also Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 700–701. ISBN 978-0-08-037941-8., where the authors note that the sulfur-oxygen bonds in SO₂ have a bond order of at least 2, based on bond length and bond energy. The octet rule is not absolute: see Hypervalent molecule for a discussion. --Ben (talk) 11:44, 11 May 2011 (UTC)

Yes, the information you are needing is in a first year chemistry book. If you ask on a talk page, you are sure to get some comments on your ideas. As Ben explained, the octet rule is just a rule, not a law.--Smokefoot (talk) 12:34, 11 May 2011 (UTC)

Thank you for your opinions. It is the certain that I need a first year chemistry book. I think, however, that the concept of bond order is part of molecular orbital theory. In contrast, the concept of resonance is part of valence bond theory. When we explain the structure of SO₂ in the context of MO theory, we do not have to use resonance structure. If we consider hybrid orbitals (e.g. sp₃d₂, sp₃d), we can explain some structures like PCl₅ and SF₆ without using MO theory. But we cannot explain the molecule that has two double bond and 10 valence electrons. This is the reason that I think the image is incorrect. --Nao1958 (talk) 12:49, 11 May 2011 (UTC)

By the way, when one of the two bonds represents a coordinate bond, the structure O=S=O is correct. But O=S=O should not be appear in the resonance theory. --Nao1958 (talk) 13:58, 11 May 2011 (UTC)

Nao1958, I think you make a good point about mixing metaphors. My image implies that sulfur uses a 3d orbital in bonding in the central structure, but not in the left and right structures. There's nothing impossible about sulfur expanding its octet by using its 3d orbitals, but computational chemistry seems to have found that it's not a very stabilising interaction and therefore not an important contributor to bonding in SO₂. In other words, the 3d orbitals of sulfur are too high in energy to be much use. O=S–O seems to be a lower energy structure, and a much more important contributor to reality.

J. Mol. Model. (2000) 6, 282–288 is the most relevant journal article I could find. It concludes that O=S=O is not a good description of SO₂ because natural bond orbital (NBO) analysis calculates O=S–O to be the best Lewis structure. I don't understand NBO well enough to determine if their conclusions are appropriate for structure drawing in Misplaced Pages. They say their NBO analysis is based on the criterion of maximum valence Lewis charge. I think this means they calculate the wavefunction of SO₂ using DFT, then apply this NBO analyser to see how well each proposed Lewis structure fits the DFT-calculated wavefunction.

If anyone can find a really trustworthy, reliable source on acceptable Lewis structures for SO₂, that would be ideal. It would be nice if we had a source that explained why SO₂ has very short, very strong sulfur-oxygen bonds, consistent with the O=S–O Lewis structure preferred by computational chemists. My guess is that although S–O is a single bond, the opposite electrical charges on S and O shorten and strengthen the bond greatly. I would guess it to be a much stronger S–O bond than the one in a molecule such as H₃C–S–O–CH₃.

We should probably rewrite this discussion and post it to Sulfur dioxide#Structure and bonding. --Ben (talk) 15:05, 11 May 2011 (UTC)

Your ablity to gather information is great. Though it is unstable, I am persuaded that O=S=O could exist and I can't judge whether the image should be deleted. Although the resonance structure is qualitative and have limits, it explains the structure of SO₂ well. I think MO is better at describing SO₂, but MO is more complicated. I think we do not have to rewrite the article at once because this kind of discussion applies to many molecules and resonance theory is easy to understand. --Nao1958 (talk) 10:31, 12 May 2011 (UTC)

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A kitten for you!

For your creation of the "Wackenroder Solution" page!

UseTheCommandLine (talk) 11:00, 29 September 2012 (UTC)