Which of the following halogens is the most reactive?

Options

A. `F_(2)`
B. `Cl_(2)`
C. `Br_(2)`
D. `I_(2)`

Answer

To determine which halogen is the most reactive among the given options (F2, Cl2, Br2, and I2), we can analyze the bond dissociation energy and the atomic properties of each halogen.

### Step-by-Step Solution:

1. **Identify the Halogens**: The halogens provided are:
- F2 (Fluorine)
- Cl2 (Chlorine)
- Br2 (Bromine)
- I2 (Iodine)

2. **Understand Bond Dissociation Energy**: Bond dissociation energy is the energy required to break the bond between two atoms. A lower bond dissociation energy means that the bond is easier to break, leading to higher reactivity.

3. **Analyze Fluorine (F2)**:
- The bond dissociation energy of F2 is very low. This is due to the small size of the fluorine atom and the high electron density around it.
- Fluorine has 7 electrons in its valence shell (1s² 2s² 2p⁵), leading to significant electron-electron repulsion between the two fluorine atoms in F2.

4. **Compare with Other Halogens**:
- Chlorine (Cl2), Bromine (Br2), and Iodine (I2) have larger atomic sizes compared to fluorine. As the size increases, the bond dissociation energy also increases.
- This means that Cl2, Br2, and I2 have stronger bonds compared to F2, making them less reactive.

5. **Conclusion**: Since F2 has the lowest bond dissociation energy, it is the most reactive halogen among the options provided.

### Final Answer:
**F2 (Fluorine) is the most reactive halogen.**

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