The most covalent halide is

Options

A. Option 1. `AlF_(3)`
B. Option 2. `AlCl_(3)`
C. Option 3. `AlBr_(3)`
D. Option 4. `Al I_(3)`

Answer

To determine the most covalent halide among the given options, we can follow these steps:

### Step 1: Understand Covalent Character
Covalent character in a compound can be influenced by the size of the ions involved. According to Fajans' rules, the covalent character increases with the size of the anion when the cation remains the same.

### Step 2: Identify the Anions
The halides in question typically involve anions from the halogen group: F⁻ (fluoride), Cl⁻ (chloride), Br⁻ (bromide), and I⁻ (iodide). We need to compare the sizes of these anions.

### Step 3: Compare Sizes of Anions
The size of the halide ions increases as you move down the group in the periodic table:
- F⁻ < Cl⁻ < Br⁻ < I⁻

This means that I⁻ is the largest among the halide ions.

### Step 4: Determine the Covalent Character
Since the covalent character is directly proportional to the size of the anion, the larger the anion, the more covalent character the compound will exhibit. Therefore, I⁻, being the largest, will have the highest covalent character.

### Step 5: Analyze the Given Options
Now, we analyze the given options:
1. AlF₃
2. AlCl₃
3. AlBr₃
4. AlI₃

Among these, AlI₃ contains the I⁻ ion, which is the largest anion and will thus exhibit the most covalent character.

### Conclusion
Therefore, the most covalent halide among the given options is **AlI₃**.

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