The coordination number of a metal in coordination compound is

Options

A. Same as primary valency
B. Sum of primary and secondary valencies
C. Same as secondary valency
D. Twice the primary valency

Answer

To determine the coordination number of a metal in a coordination compound, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Coordination Compound**:
Let's denote the coordination compound as M L X Y P, where:
- M = Metal atom
- L = Ligands (molecules or ions that donate electron pairs to the metal)
- X, Y, P = Other components (which may include counter ions or additional ligands)

2. **Understand the Valencies**:
- The coordination number is related to the number of ligands (L) directly bonded to the metal (M).
- The primary valency (Y) is outside the coordination sphere and does not contribute to the coordination number.
- The secondary valency (L) is inside the coordination sphere and is what we focus on to determine the coordination number.

3. **Count the Ligands**:
- The coordination number is equal to the total number of ligand donor atoms surrounding the metal atom in the coordination sphere.
- For example, if there are 4 ligands (L) attached to the metal, the coordination number would be 4.

4. **Conclusion**:
- The coordination number of the metal in the coordination compound is equal to the number of ligands (L) that are directly bonded to it, which corresponds to the secondary valency.

### Final Answer:
The coordination number of the metal in the coordination compound is equal to the secondary valency.

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