Iodine forms` I_3^(-)` but `F_2` does not form `F_(3)^(-)` ions. Why?

Explanation

To understand why iodine forms the ion \( I_3^{-} \) while fluorine does not form \( F_3^{-} \), we can break down the explanation into several steps:

### Step 1: Atomic Size
- **Explanation**: Iodine is larger in size compared to fluorine. The larger atomic radius of iodine allows it to accommodate more electrons in its outer shell.
- **Conclusion**: The larger size of iodine facilitates the formation of larger anions like \( I_3^{-} \).

### Step 2: Presence of d-Orbitals
- **Explanation**: Iodine has available d-orbitals that allow it to expand its valence shell beyond the octet rule. This means iodine can accommodate more than 8 electrons in its outer shell.
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