Formation of interstitial compound makes the transition metal

Options

A. More soft
B. More ductile
C. More metallic
D. More hard

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Interstitial Compounds**: Interstitial compounds are formed when small atoms (such as hydrogen, carbon, nitrogen, or oxygen) occupy the interstitial spaces (holes) in the crystal lattice of a metal.

2. **Role of Transition Metals**: Transition metals have a unique ability to form these interstitial compounds due to their metallic bonding and the presence of vacant d-orbitals. This allows them to accommodate smaller atoms within their structure.

3. **Types of Holes**: In a crystal lattice, there are different types of holes where smaller atoms can fit. The two main types are:
- **Octahedral holes**: Larger spaces that can accommodate larger atoms.
- **Tetrahedral holes**: Smaller spaces that can accommodate smaller atoms.

4. **Formation of Covalent Bonds**: When small atoms occupy these interstitial spaces, they can form covalent bonds with the transition metal atoms. This bonding alters the electronic structure and properties of the metal.

5. **Effects on Properties**: The formation of interstitial compounds typically increases the hardness and rigidity of the transition metal. The covalent bonds created by the small atoms contribute to these enhanced properties.

6. **Conclusion**: Therefore, the formation of interstitial compounds makes transition metals harder and more rigid due to the presence of covalent bonds formed between the metal and the small interstitial atoms.

**Final Answer**: The formation of interstitial compounds makes transition metals harder and more rigid.

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