According to Werner's theory, how many types of valencies are shown by central metal atom?

Options

A. 1
B. 2
C. 3
D. 4

Answer

**Step-by-Step Solution:**

1. **Understanding Werner's Theory**: According to Werner's theory, coordination compounds consist of a central metal atom bonded to various ligands. This theory distinguishes between different types of valencies exhibited by the central metal atom.

2. **Types of Valencies**: Werner proposed that there are two types of valencies:
- **Primary Valency**: This refers to the oxidation state of the central metal atom. It indicates how many electrons the metal can lose to form bonds. The primary valency is satisfied by anions that balance the charge of the metal.
- **Secondary Valency**: This is related to the coordination number of the metal, which represents how many ligands are directly bonded to the metal atom. It reflects the geometry of the coordination complex.

3. **Example for Clarification**: Consider a coordination compound such as [Co(NH3)5Cl]Cl2. In this example:
- The primary valency is satisfied by the chloride ion (Cl-) which balances the charge of the cobalt ion.
- The secondary valency is satisfied by the five ammonia (NH3) ligands that are directly coordinated to the cobalt ion.

4. **Conclusion**: Based on Werner's theory, the central metal atom exhibits two types of valencies: primary and secondary. Therefore, the answer to the question is that the central metal atom shows **2 types of valencies**.

**Final Answer**: The central metal atom shows **2 types of valencies** according to Werner's theory.

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