Question

Explain coordination number by an example.

Hint:

Common coordination numbers are 2, 4, and 6, which lead to geometries like linear, tetrahedral/square planar, and octahedral respectively.

Answer 1

Step 1: Definition.
Coordination number is defined as the number of ligand donor atoms that are directly bonded to the central metal atom or ion in a coordination compound.
Step 2: Explanation.
It tells us how many atoms, ions, or molecules are attached to the central atom in a complex. This depends on the size, charge, and electronic configuration of the central atom.
Step 3: Example.
In the complex \([Co(NH_3)_6]^{3+}\):
- The central metal ion is \(Co^{3+}\).
- Six ammonia molecules (\(NH_3\)) are bonded directly to cobalt.
Thus, the coordination number of cobalt is 6. Conclusion:
The coordination number represents the total number of bonds formed between the central metal ion and the surrounding ligands.