Explain the bonding in coordination compounds in terms of Werner's postulates?

Explanation

(i) Every metal atom or ion have two types of valencies, primary valency.as well as secóndary valency.
(ii) Primary valency is same as oxidation state. It is saitisfied only by negatively charged ions.
iii) Secondary valency is same as coordination number.
iv) Primary valency is ionisable whereas secondary valency is non-ionisable.
(v) Prịmary -valency is non directional whereas secondary valency is directional i:e., determines shapes of complexes.