Why is sulfur the central atom in the Lewis structure for SO2?

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

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?

• can you give example for "two or more atoms for the central element"? – Freddy Jul 16 '15 at 7:43
• @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? – Voldemort Jul 16 '15 at 7:54
• I don't know any such molecule. But you can check out chemwiki.ucdavis.edu/Organic_Chemistry/Fundamentals/… – Freddy Jul 16 '15 at 8:06
• @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)? – Voldemort Jul 16 '15 at 8:09
• Let's say left oxygen is A and right oxygen is B. Initially both oxygen(without hydrogen) would have 3 lone pair of electron. Then 1st hydrogen will attach lets say oxygen A. Now oxygen A will have 2 lone pair of electrons and oxygen B have 3 lone pair of electron. So naturally 2nd hydrogen will attract towards oxygen B and not to oxygen A. – Freddy Jul 16 '15 at 9:49