Hardness of transition metals is due to

Options

A. Large atomic size
B. Metallic bonding
C. Ionic bond
D. High ionization energy

Answer

To determine the reason for the hardness of transition metals, we can analyze the options provided and understand the underlying concepts.

### Step-by-Step Solution:

1. **Understanding Transition Metals**: Transition metals are found in the d-block of the periodic table. They are characterized by the presence of d electrons, which play a significant role in their chemical properties.

2. **Evaluating the Options**:
- **Option 1: Large Atomic Size**: While atomic size can influence properties, it does not directly correlate with hardness. Larger atoms typically have weaker metallic bonds.
- **Option 2: Metallic Bonding**: Transition metals exhibit strong metallic bonding due to the presence of delocalized d electrons. This type of bonding contributes significantly to the hardness of these metals.
- **Option 3: Ionic Bonding**: Ionic bonding is not a characteristic of transition metals. Instead, they primarily exhibit metallic and covalent bonding.
- **Option 4: High Ionization Energy**: High ionization energy indicates that it requires a lot of energy to remove an electron, but it does not directly explain the hardness of the metal.

3. **Conclusion**: The hardness of transition metals is primarily due to **metallic bonding**. The presence of unpaired d electrons allows for strong metallic bonds, which enhances the hardness and strength of the metal.

### Final Answer:
The hardness of transition metals is due to **metallic bonding**.

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