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So apparently the Lewis structure of $\ce{SO_2}$ is

enter image description here

It was my understanding that the central atom is the one that is more electronegative. And an atom is more electronegative the closer it is to Fluorine (top-right). Oxygen is definitely closer to fluorine than sulfur is. Then, why is sulfur the central atom?

Also, one thing that has been bugging me for a while: if there are two or more atoms for the central element, how do you make the Lewis structure?

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  • $\begingroup$ can you give example for "two or more atoms for the central element"? $\endgroup$
    – Freddy
    Jul 16, 2015 at 7:43
  • $\begingroup$ @Freddy I don't have an example, but I imagine there could be a molecule with two types of elements, and the least electronegative one happens to have two or more atoms. Or is such a thing impossible? $\endgroup$
    – Voldemort
    Jul 16, 2015 at 7:54
  • $\begingroup$ I don't know any such molecule. But you can check out chemwiki.ucdavis.edu/Organic_Chemistry/Fundamentals/… $\endgroup$
    – Freddy
    Jul 16, 2015 at 8:06
  • $\begingroup$ @Freddy how about H2O2 (just found it in the book)? Oxygen is the central since Hydrogen can't ever be. But I got two oxygens. Apparently the structure looks like this: i.stack.imgur.com/Y39wf.png, but I don't get it: shouldn't the two hydrogens be connected to the same oxygen (because it is the central)? $\endgroup$
    – Voldemort
    Jul 16, 2015 at 8:09
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    $\begingroup$ Being the central atom has nothing to do with electronegativity. Sometimes the central atom is the most electronegative, sometimes it is the least electronegative. $\endgroup$
    – Ivan Neretin
    Jan 15, 2017 at 19:01

2 Answers 2

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I think you messed up something. Because it is exactly opposite.

"Central part of atom is normally least(not the most) electronegative atom i.e. S in this case.

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    $\begingroup$ What about H2O ? $\endgroup$
    – Shahbaaz1104
    Jul 11, 2017 at 16:29
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For polyatomic molecule least electronegative polyvalent atom acts as central atom and by using this we wlll get most plausible structure (structure having least magnitude of formal charge) for polyatomic molecule.

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