I looked this question up and still couldn't understand.
Why, in \ce{SO4^2-} don't the 4 oxygens create double bonds.
In that case the all the oxygens will have 0 formal charge while the sulfur will have -2.
In what I've seen only 2 oxygens create double bonds making the sulfur have no formal charge, 2 oxygens have -1 formal charge and 2 others no formal charge.
When comparing formal charge of -2 on the sulfur, it is indeed less stable than no formal charge at all, and that is why it should be the most common resonance structure.
But everywhere I looked that was not the case, \ce{SO4^2-} only created 2 double bonds and I cant understand why.
Cant the oxygens create coordination bonds with the sulfur?
