Which halide of magnesium has highest ionic character?

Options

A. Chloride
B. Bromide
C. Iodide
D. Fluoride

Answer

To determine which halide of magnesium has the highest ionic character, we can analyze the properties of the halides involved: magnesium chloride (MgCl2), magnesium bromide (MgBr2), magnesium iodide (MgI2), and magnesium fluoride (MgF2).

### Step-by-step Solution:

1. **Understanding Ionic Character**:
Ionic character refers to the extent to which a bond between two atoms has ionic characteristics, as opposed to covalent characteristics. Factors influencing ionic character include the size of the ions and their polarizability.

2. **Identify the Halides**:
The halides of magnesium we are considering are:
- Magnesium Chloride (MgCl2)
- Magnesium Bromide (MgBr2)
- Magnesium Iodide (MgI2)
- Magnesium Fluoride (MgF2)

3. **Size and Polarizability of Halides**:
- The size of the halide ions increases from fluoride (F-) to chloride (Cl-), bromide (Br-), and iodide (I-).
- Smaller ions are less polarizable, while larger ions are more polarizable. Therefore, F- is the smallest and least polarizable, while I- is the largest and most polarizable.

4. **Ionic Character Trend**:
- The ionic character generally increases with the increase in the size of the anion because larger anions can better stabilize the positive charge of the cation (Mg2+).
- However, the ionic character also depends on the charge density of the cation. Magnesium has a +2 charge, which increases its ability to polarize the anions.

5. **Comparison of Halides**:
- **MgF2**: Magnesium fluoride has a high ionic character due to the small size of the fluoride ion and the high charge density of the magnesium ion.
- **MgCl2**: Magnesium chloride has a lower ionic character than MgF2 due to the larger size of Cl- compared to F-.
- **MgBr2**: Similarly, magnesium bromide has even lower ionic character than MgCl2.
- **MgI2**: Magnesium iodide has the least ionic character due to the large size and high polarizability of the iodide ion.

6. **Conclusion**:
Based on the analysis, magnesium fluoride (MgF2) has the highest ionic character among the magnesium halides.

### Final Answer:
The halide of magnesium with the highest ionic character is **Magnesium Fluoride (MgF2)**.