Hello,

Postulates of Werner's Theory of coordination compounds.

• Central metal ion in a complex shows two types of valences primary valence and secondary valence.
• The primary valence is ionisable and satisfied by negative ions
• Secondary valence is non ionisable.It is equal to the coordination number of central metal ion or atom. It is fixed for a metal.Secondary valencies are satisfied by negative ions or neural molecules.
• The primary valence  is non directional. The secondary valence is directional. Ions or molecules attached to satisfy secondary valences have characteristic spatial arrangements. Secondary valence decides geometry of the complex compound.