Here we're going to talk about chelating agents. Now bidentate and polydentate ligands, or ligands are considered chelating agents. Now a chelating agent, they create ring structures in a complex ion when donor atoms bond to the central atom, a metal which we're going to call M.

So here what do we have? We have this is monodentate, this is monodentate and this here is our bidentate ligand or ligand attached. Those two nitrogens each had a lone pair which they used to connect to the metal and as we can see we created a ring on the left side. This here would represent its overall complex ion structure formula.

Now here we're going to say complex formed with chelating agents are more stable than with monodentate ligands. And when we talk about stability of these rings, ideally we're trying to make five or six membered rings if we were to count this out with C 123455. And six membered rings are pretty common when it comes to these bidentate and polydentated ligands or ligands, right. So just keep that in mind when we're looking at different types of attachments that occur when they connect to our central metal.