Question

Explain Werner's theory of co-ordination compounds?

Answer 1

Central metal atom shows two types of valencies:
(i) Primary (principal) valency. It represents oxidation number of the metal. It is non directional and usually written outside the coordination sphere. It does not give the idea of geometry of the coordination compounds. It is shown by dotted line.
(ii) Secondary (auxillary valence). It represents coordination number of metal.
The metal atom tries to satisfy both its valencies. It is directional and usually written inside the coordination sphere. It gives definite geometry to coordination compounds. It is shown by solid line.