I'm currently preparing my exam and while I did never think about this question during the course, it begins to confuse me right now...
Why is it the structure of $\ce {ClO_{2}-}$ like $\ce {O-Cl-O}$ and not like $\ce {O-O-Cl}$?
I know how to place the covalent bonds and the electrons, but I don't know how to figure out the basic structure of the molecule. Is there a relatively simple rule to solve (and understand) such relatively simple molecules?