Group 2 hydrides with significant covalent character is/are

Options

A. `BeH_(2)`
B. `MgH_(2)`
C. `CaH_(2)`
D. Both (1) & (2)

Answer

To determine which Group 2 hydrides exhibit significant covalent character, we need to analyze the electronegativity values of the elements involved in the hydrides. The key concept here is that the smaller the difference in electronegativity between the metal and hydrogen, the more covalent character the hydride will have.

### Step-by-Step Solution:

1. **Identify the Group 2 Hydrides**: The hydrides in question are BeH₂ (Beryllium hydride), MgH₂ (Magnesium hydride), and CaH₂ (Calcium hydride).

2. **Find Electronegativity Values**:
- Beryllium (Be) has an electronegativity of approximately 1.57.
- Magnesium (Mg) has an electronegativity of approximately 1.31.
- Calcium (Ca) has an electronegativity of approximately 1.00.

3. **Calculate the Difference in Electronegativity**:
- For BeH₂: Difference = |1.57 - 2.20| = 0.63 (Hydrogen's electronegativity is approximately 2.20)
- For MgH₂: Difference = |1.31 - 2.20| = 0.89
- For CaH₂: Difference = |1.00 - 2.20| = 1.20

4. **Analyze the Differences**:
- The smaller the difference in electronegativity, the more covalent character the hydride will have.
- BeH₂ has the smallest difference (0.63), followed by MgH₂ (0.89), and CaH₂ has the largest difference (1.20).

5. **Conclusion**:
- Since BeH₂ and MgH₂ have smaller differences in electronegativity compared to CaH₂, they exhibit significant covalent character.
- Thus, the Group 2 hydrides with significant covalent character are BeH₂ and MgH₂.

### Final Answer:
The Group 2 hydrides with significant covalent character are BeH₂ and MgH₂.

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