Identify the ligands in the following complex ions?

Question

[AIF4]-
[Cu(NH3)4]2+
[FeCDTA]3+

I would really like to see the process to get the answer to this. This question is on a practice test.

Answer 1

The central ion is the biggest one
In [AlF4]- Al is the central ion it has a charge 3+. The four F4 have together a charge -4 so, it is normal that AlF4, f beiing the ligand has a charge -1

In [Cu (NH3)4], the group NH3 ammonium is the ligand. NH3 is uncharged and Cu has a charge +2

[FeCDTA] has fFe as central ion with charge 3+ and CDTA as ligand

Answer 2

A hint here is that there will always be more of the ligand. In complex ions such as the ones you've listed, there is always one central atom (usually a metal or a cation, anything positively charged) which is surrounded by several ligand atoms (anything electron rich). For example, AlF4 consists of FOUR flouro atoms and ONE Al atom. Because Al is the metal atom and a cation (positively charged), it is the central atom and F is the ligand.

Answer 3

now complex ions are made up of a central ion, and then you have the ligands all around it, all bound to it, but not among each other.
so when you have a metal, it is usually the the complexing ion, and all the rest (in most cases, surely in such simple ones) are ligands.
so if Al is the metal ion, all the F- have to be ligands.
so are the 4 NH3 molecules
and so is the EDTA.