Werner in 1893 put forward a theory, known as Werner's co-ordination theory. Some important postulates of this theory are as below:

(1) Each metal ion possesses two types of valency

(i) Primary or principle or ionisable valency

(ii) Secondary or subsidary or non-ionisable valency.

(2) Primary valencies are satisfied by anions only. The number of primary valencies depend upon the oxidation state of central metal. These are represented by dotted lines in between the central metal atom and anion.

(3) The secondary valencies are satisfied by the ions or the neutral electron pair donor molecules. These are represented by solid lines. Secondary valency is also known as co-ordination number.

(4) The ions attached by secondary valencies do not ionise when the complex is dissolved in a solvent.

Which of the following is/are the limitations of Werner's Theory?

All of these

Limitations of Werner's Theory

This theory does not explain

(1) Nature of bonding in complexes

(2) Colour of the complexes

(3) Magnetic properties of the complexes

(4) Werner studied a few complexex of Co and Cr