Which one of the following has strongest metallic bonding ?

Options

A. Fe
B. Sc
C. V
D. Cr

Answer

To determine which of the given metals has the strongest metallic bonding, we need to analyze the number of unpaired electrons in their electronic configurations. The strength of metallic bonding is directly proportional to the number of unpaired electrons; more unpaired electrons result in stronger metallic bonds.

### Step-by-Step Solution:

1. **Identify the Metals and Their Electronic Configurations:**
- Iron (Fe): The electronic configuration is \( [Ar] 4s^2 3d^6 \).
- Scandium (Sc): The electronic configuration is \( [Ar] 4s^2 3d^1 \).
- Vanadium (V): The electronic configuration is \( [Ar] 4s^2 3d^3 \).
- Chromium (Cr): The electronic configuration is \( [Ar] 4s^1 3d^5 \).

2. **Count the Number of Unpaired Electrons:**
- **Iron (Fe)**:
- 4s has 2 electrons (paired).
- 3d has 6 electrons (1, 2, 3, 4, 5, 6) which means there are 4 unpaired electrons (due to Hund's rule).
- **Scandium (Sc)**:
- 4s has 2 electrons (paired).
- 3d has 1 electron (unpaired).
- Total unpaired electrons = 1 (from 3d).
- **Vanadium (V)**:
- 4s has 2 electrons (paired).
- 3d has 3 electrons (1, 2, 3) which means there are 3 unpaired electrons.
- **Chromium (Cr)**:
- 4s has 1 electron (unpaired).
- 3d has 5 electrons (1, 2, 3, 4, 5) which means there are 6 unpaired electrons (due to Hund's rule).

3. **Summarize the Number of Unpaired Electrons:**
- Iron (Fe): 4 unpaired electrons
- Scandium (Sc): 1 unpaired electron
- Vanadium (V): 3 unpaired electrons
- Chromium (Cr): 6 unpaired electrons

4. **Determine the Metal with the Strongest Metallic Bonding:**
- Since the strength of metallic bonding is directly related to the number of unpaired electrons, we can conclude:
- Chromium (Cr) has the most unpaired electrons (6), thus it has the strongest metallic bonding.

### Conclusion:
The metal with the strongest metallic bonding among the options given is **Chromium (Cr)**.