Determining -dentate

[Brooke Gushiken 1B]

Hi! I was a little confused on how we can determine monodentate, bidentate, or polydentate. Does it just depend on the amount of lone pairs on the molecule, or are there other factors to take into account as well? Also, I was wondering how this concept relates to the chelating groups. Thank you so much!

[Ella Henrickson 3I]

Hey! It depends on the number of sites that the ligand is binding at. So,
1 site = monodentate
2 sites = bidentate
3 sites = tridentate
6 sites = hexadentate
(each site means the donation of 1 electron pair)

Looking at chelating groups, any polydentate (more than one site) ligand can form a chelate structure. This is because they can bind to the same central metal atom at least twice to form a ring-like structure.