is primary valence same as oxidation number.if so if it satisfies secondary valence as well how can we say it is ionisable?

Dear isha,

Werner put forward this theory to explain various properties of co-ordination compounds. Some important points about this theory are:

1. The central metal atom in complex has two types of valencies, one is Primary valency and Second is Secondary valency.
2. The primary valencies indicate the oxidation state of the central metal atom while the secondary valency indicate about the co-ordination number of the metal atom.
3. Primary valencies are ionizable whereas secondary valencies non-ionizable.
4. Primary valencies are satisfied by Negative ions while secondary ions are satisfed by neutral or -ve groups.
5. In complexes, the ligands are projected in space about the central metal atom to give a specific shape to the complex.
6. Complexes also possess the property of exchange of ions. Ions outside ionization sphere can easily come inside the sphere and bond with the central metal atom losing their ionic character and gaining co-ordinate covalent character or vice-versa.