How to determine the charge of ligands?

[Nancy Yao]

I am confused how to determine the charge of each specific ligand, like Cl, NH3, H2O, NH2, etc.

[805593945]

I think you just gotta remember it, like how you remember the charge for polyatomic molecules/ions.

[Katherine_Douglas_1F]

It is useful to use the periodic table. All the halogens in group 17 (F, Cl, Br, I) have a charge of -1. Think of it as being one removed from the noble gases. They gain one electron to get a complete shell, making the charge -1. In the same logic, group 16 elements (O, S) need two electrons to get a full shell, making their charge -2. The group one (Li, Na, K) and group two (Be, Mg, Ca) metals lose one or two electrons, respectively, to get a full shell. This makes their charges +1 and +2 respectively. Everything else you can figure out by using these. The transition metals have varying charges, so you have to do the math to figure out what they are going to be. H2O (+2 + -2=0) and NH3 (-3 + +3=0) are both neutral. NH2 is -1 (-3 + +2= -1).

[Nick Pascua 2L]

Hi!

There are different ways to find the charge of ligands. However, it depends on the ligand. Some require just memorization or drawing out the Lewis structures to see if it makes sense. Others you can figure out by doing math from multiple elements/compounds found in complexes.

[allyssa bradley 1H]

For molecules, you could try using formal charge, or the charge of each atom known from the periodic table (for example, NH3 is stable because N is 5- and H is 1+, which all cancels).