Which of the following halides has the maximum covalent character ?

Options

A. LiI
B. NaI
C. KI
D. CsI

Answer

To determine which halide has the maximum covalent character among the given options (LiI, NaI, KI, CaI2), we can analyze the polarizing power of the cations and the size of the anions involved. Here's a step-by-step solution:

### Step 1: Understand Covalent Character
Covalent character in ionic compounds arises when there is a significant difference in the electronegativity of the ions involved, leading to polarization of the electron cloud of the anion by the cation. The smaller the cation and the larger the anion, the greater the covalent character.

### Step 2: Identify the Cations and Anions
The compounds given are:
- LiI (Lithium Iodide)
- NaI (Sodium Iodide)
- KI (Potassium Iodide)
- CaI2 (Calcium Iodide)

Here, the cations are Li⁺, Na⁺, K⁺, and Ca²⁺, and the anion is I⁻ for all except CaI2, which has two I⁻ ions.

### Step 3: Compare the Size of Cations
The polarizing power of a cation is inversely proportional to its size:
- Li⁺ (smallest cation)
- Na⁺ (larger than Li⁺)
- K⁺ (larger than Na⁺)
- Ca²⁺ (larger than K⁺ but has a higher charge)

Among these, Li⁺ has the highest polarizing power due to its small size.

### Step 4: Analyze the Anion
The anion in all cases is I⁻, which is relatively large. The larger the anion, the more easily it can be polarized by the cation.

### Step 5: Determine Covalent Character
Since Li⁺ is the smallest cation with the highest polarizing power, it will polarize the I⁻ ion more effectively than the other cations. Thus, LiI will exhibit the maximum covalent character among the given halides.

### Conclusion
The halide with the maximum covalent character is **LiI (Lithium Iodide)**.