Achieve Problem 9C 5 part A

[905767718]

The question asks for the denticity of carbonate, CO3 2-, and the answer key says that it is both mono and bidentate. I was wondering why it can be monodentate since I thought there were 2 binding sites unless there's a resonance structure that I'm missing or something?

[Allison Peng 1D]

I think it can be monodentate or bidentate depending on the orientation of the binding. In order for it to be bidentate when binding to a central atom, two of the oxygens have to be facing the central atom, forming a sort of prong. If it turned a bit and only one oxygen was facing the central atom, I believe it would be monodentate.