Question

Write postulates of Werner theory of co-ordination complexes.

Answer 1

1. In coordination compounds, metal ions show two types of valencies:
   1. Primary (ionizable) valency and
   2. secondary (nonionizable) valency
2. The ionizable sphere consists of entities that satisfy the primary valency of the metal. Primary valencies are generally satisfied by anions.
3. The secondary valencies are non-ionizable and are satisfied by neutral molecules or negative ions. Every metal atom has a fixed secondary valency or coordination number.
4. The ions/groups attached to secondary valencies with the metal have characteristic spatial arrangement, i.e., are directed towards a fixed position in space, which leads to the defined geometry of coordination compounds.