In Werner's theory, each metal ion possesses how many types of valency?

2

The correct answer is option 1. 2.

In Werner's theory of coordination compounds, developed by Alfred Werner in the late 19th and early 20th centuries, each metal ion is proposed to possess two types of valency, namely primary valency and secondary valency.

Primary Valency: The primary valency is essentially the oxidation state or charge of the metal ion. It is determined by the number of electrons the metal has lost or gained to achieve a stable configuration. This valency dictates the number of ligands that can coordinate to the metal ion in the complex.

For example, if a metal ion has a +2 charge, it will typically exhibit a primary valency of 2, meaning it can coordinate with two ligands to form a complex.

Secondary Valency: The secondary valency, also known as the coordination number or secondary oxidation state, represents the actual number of ligands that are attached to the metal ion in the complex. Unlike the primary valency, which is fixed by the charge of the metal ion, the coordination number can vary depending on the nature of the ligands and the geometry of the complex.

For instance, a metal ion with a primary valency of 2 can have a coordination number of 4 in a tetrahedral complex or 6 in an octahedral complex, depending on the ligands attached.

The secondary valency is essentially a measure of the metal ion's ability to form coordination bonds with ligands, and it determines the geometry of the complex.

Overall, Werner's theory provides a framework for understanding the structures and bonding in coordination compounds by considering the concept of primary and secondary valencies. This theory laid the foundation for modern coordination chemistry and has greatly influenced our understanding of metal-ligand interactions in complex systems.