Which of alkaline earth metal halides given below is essentially covalent in nature?

Options

A. `BeCl_(2)`
B. `MgCl_(2)`
C. `SrCl_(2)`
D. `CaCl_(2)`

Answer

To determine which alkaline earth metal halide is essentially covalent in nature, we can follow these steps:

### Step 1: Understand the nature of alkaline earth metal halides
Alkaline earth metal halides are compounds formed between alkaline earth metals (Group 2 elements like Be, Mg, Ca, Sr, Ba) and halogens (Group 17 elements like F, Cl, Br, I). These compounds can exhibit either ionic or covalent character depending on the size and charge of the metal cation and the halide anion.

**Hint:** Consider the factors that influence ionic vs. covalent character, such as size and charge of ions.

### Step 2: Analyze the size and charge of the cations
Among the alkaline earth metals, beryllium (Be) has the smallest size and a relatively high charge density due to its +2 charge. This high charge density leads to a stronger polarization of the electron cloud of the halide ions.

**Hint:** Remember that smaller cations with higher charges tend to polarize anions more effectively.

### Step 3: Consider the polarization effect
When a cation can polarize an anion significantly, the bond between them tends to have more covalent character. In the case of BeCl2, the small size of Be and its high charge lead to a significant polarization of the chloride ions, making the bond more covalent.

**Hint:** Think about how polarization affects the bond character between metal and halide.

### Step 4: Compare with other alkaline earth metal halides
Other alkaline earth metal halides like MgCl2, CaCl2, etc., have larger cations compared to Be. As a result, they exhibit more ionic character due to lower polarization effects.

**Hint:** Compare the size and charge of other alkaline earth metals to Be and analyze their polarization ability.

### Step 5: Conclusion
Based on the analysis, BeCl2 is identified as the alkaline earth metal halide that is essentially covalent in nature due to the high polarization caused by the small size and high charge of the beryllium cation.

**Final Answer:** BeCl2 is essentially covalent in nature.