Highest covalent character is found in

Options

A. `CaF_2`
B. `CaCl_2`
C. `CaBr_2`
D. `CaI_2`

Answer

To determine which compound has the highest covalent character among the given options (CaF2, CaCl2, CaBr2, CaI2), we can apply Fajans' rules. Here’s a step-by-step solution:

### Step 1: Understand Fajans' Rules
Fajans' rules state that the covalent character of an ionic bond increases with:
- The small size of the cation.
- The large size of the anion.
- The high positive charge on the cation.

### Step 2: Identify the Cation and Anions
In all the given compounds, the cation is calcium (Ca²⁺). The anions are:
- CaF2: F⁻ (fluoride)
- CaCl2: Cl⁻ (chloride)
- CaBr2: Br⁻ (bromide)
- CaI2: I⁻ (iodide)

### Step 3: Compare the Sizes of Anions
According to periodic trends, the size of the anions increases as we move down the group in the periodic table:
- I⁻ > Br⁻ > Cl⁻ > F⁻

This means that I⁻ is the largest anion, followed by Br⁻, Cl⁻, and F⁻.

### Step 4: Analyze the Effect of Anion Size on Covalent Character
A larger anion (I⁻) is more easily polarizable than a smaller anion (F⁻). This means that the larger the anion, the more it can be distorted by the cation, leading to a higher covalent character.

### Step 5: Conclusion
Since CaI2 contains the largest anion (I⁻), it will have the highest covalent character among the given options.

### Final Answer
The compound with the highest covalent character is **CaI2**.

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