Write the postulates of Warner's theory.

Explanation

(i) . Every metal atom has two types of valencies Primary valency or ionisable valancy Secondary valency or non ionisable valency
(ii) The primary valancy corresponds to the oxidation state of metal ion. It is always satisfied by negative ions.
(iii) Secondary valency corresponds to the coordination number of the metal ion or atom.It is satisfied by either negative ions or neutral molecules.
(iv) The molecules or ions that satisfy secondary valencies are called ligands
(v) The ligands which satisfy secondary valencies must project in definite directios in space. So that secondary valencies are directional in nature whereas the primary valencies are non-directional in nature.
(vi) . The ligand have unshared pair of electrons.These unshared pair of electrons are donated to central metal ion or atom in a compound.Such compounds are called coordination compounds.
Werner's representation
E.g: ` [Co(NH_3)_6]Cl_3`
Cl : Primary valency (dotted lines ) ` NH_3 ` secondary valency (solid lines )
Defects of Werner's theory
Werner's theory describes the structures of many co-ordination compounds successfully However ,it does not explain the magnetic and spectral properties