Which of the following is the correct order of radius ?

Options

A. `H^(-)gtHgtH^+`
B. `Na^(+) gtF^(-)gtO^(2-)`
C. `F^(-) gtO^(2-)gt Na^+`
D. `Al^(3+)gtMg^(2+)gtN^(3-)`

Answer

To determine the correct order of radius for the given species, we will analyze the ions and their electron configurations step by step.

### Step 1: Analyze H-, H, and H+
- **H- (Hydride Ion)**: Contains 2 electrons and 1 proton. The presence of an extra electron increases the electron-electron repulsion, leading to a larger radius.
- **H (Neutral Hydrogen Atom)**: Contains 1 electron and 1 proton. It has a smaller radius compared to H- because it has less electron-electron repulsion.
- **H+ (Hydrogen Ion)**: Contains no electrons and only 1 proton. This results in a very small radius since there are no electrons to repel each other.

**Order of radius**: H- > H > H+

### Step 2: Analyze Na+, F-, and O2-
- **Na+ (Sodium Ion)**: Contains 10 electrons (after losing one electron) and has 11 protons. The effective nuclear charge is relatively high, pulling the electrons closer.
- **F- (Fluoride Ion)**: Contains 10 electrons (after gaining one electron) and has 9 protons. The lower nuclear charge compared to Na+ means that the electrons are held less tightly, resulting in a larger radius.
- **O2- (Oxide Ion)**: Contains 10 electrons (after gaining two electrons) and has 8 protons. With the least nuclear charge, the electrons are held the least tightly, leading to the largest radius.

**Order of radius**: O2- > F- > Na+

### Step 3: Analyze Al3+, Mg2+, and Ne
- **Al3+ (Aluminum Ion)**: Contains 10 electrons and has 13 protons. The high nuclear charge pulls the electrons very close, resulting in a small radius.
- **Mg2+ (Magnesium Ion)**: Contains 10 electrons and has 12 protons. The nuclear charge is less than that of Al3+, resulting in a larger radius than Al3+.
- **Ne (Neon)**: Contains 10 electrons and has 10 protons. The nuclear charge is lower than that of Al3+ and Mg2+, giving it a larger radius than Al3+ but smaller than Mg2+.

**Order of radius**: Al3+ < Mg2+ < Ne

### Final Summary of Radius Orders
1. **For H-, H, H+**: H- > H > H+
2. **For Na+, F-, O2-**: O2- > F- > Na+
3. **For Al3+, Mg2+, Ne**: Al3+ < Mg2+ < Ne