Coordination complexes
Transition metals (and to some extent other metals) form coordination complexes in which the metal or metal ion is associated with ligands.
In most complexes the metal is associated with more than one ligand.
The number of ligands associated with the metal is the coordination number.
Coordination numbers can't easily be predicted, but 2, 4 and 6 are common.
For Ag(NH3)2+ the coordination number is 2.
The overall charge on the complex is equal to the sum of the charges on its component parts.
| M metal Lewis acid electron deficient | + | :L ligand Lewis base nonbonding pair |  | M : L |
In most complexes the metal is associated with more than one ligand.
The number of ligands associated with the metal is the coordination number.
Coordination numbers can't easily be predicted, but 2, 4 and 6 are common.
For Ag(NH3)2+ the coordination number is 2.
The overall charge on the complex is equal to the sum of the charges on its component parts.
The oxidation number on the metal can be deduced if the charge on the ligands is known.
As NH3 has no charge, Ag in Ag(NH3)2+ is +1.
As NH3 has no charge, Ag in Ag(NH3)2+ is +1.