Which one of the following ions has the highest value of ionic radius?

Options

A. `Li^+`
B. `B^(3+)`
C. `O^(2-)`
D. `F^-`

Explanation

To determine which ion has the highest value of ionic radius among the given options, we will analyze the ionic radii of each ion provided. The options are:

1. Li⁺ (Lithium ion)
2. B (Boron, neutral atom)
3. O²⁻ (Oxide ion)
4. F⁻ (Fluoride ion)

### Step 1: Understand Ionic Radius Trends
Ionic radius is influenced by the charge of the ion and the number of electrons. Generally:
- Anions (negatively charged ions) are larger than their neutral atoms because they gain electrons, which increases electron-electron repulsion and expands the electron cloud.
- Cations (positively charged ions) are smaller than their neutral atoms because they lose electrons, reducing electron-electron repulsion and pulling the remaining electrons closer to the nucleus.

### Step 2: Analyze Each Ion
1. **Li⁺**: Lithium loses one electron to form Li⁺. It has 2 electrons left, leading to a smaller radius compared to neutral lithium.
2. **B**: Neutral boron has a certain radius, but it is not an ion, so we won't consider it for the highest ionic radius.
3. **O²⁻**: Oxygen gains two electrons to form O²⁻. It has 10 electrons and a higher electron-electron repulsion, resulting in a larger ionic radius.
4. **F⁻**: Fluoride gains one electron to form F⁻. It has 10 electrons as well, but less electron-electron repulsion compared to O²⁻.

### Step 3: Compare Ionic Radii
- **Li⁺**: Smallest radius due to loss of an electron.
- **B**: Not an ion, so not applicable.
- **O²⁻**: Largest radius due to gaining two electrons and increased repulsion.
- **F⁻**: Larger than Li⁺ but smaller than O²⁻.

### Conclusion
The ion with the highest ionic radius among the given options is **O²⁻ (Oxide ion)**.

### Final Answer
**O²⁻ has the highest value of ionic radius.**

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