Which one of the following is correct order of the size of iodine species ?

Options

A. `I gt `I^(-)` gt `I^(+)`
B. `I^(+)` gt `I^(-)` gt I`
C. `I gt `I^(+)` gt `I^(-)`
D. `I^(+)` gt I gt `I^(-)`

Explanation

To determine the correct order of the size of iodine species (I, I⁻, I⁺), we need to understand how the addition or removal of electrons affects the size of an atom. Here’s a step-by-step solution:

### Step 1: Identify the Species
We have three species of iodine to compare:
- Neutral iodine atom (I)
- Iodide ion (I⁻) - an anion
- Iodine cation (I⁺) - a cation

### Step 2: Understand Electron Gain and Loss
- **Anion (I⁻)**: When iodine gains an electron, it becomes negatively charged. The addition of an electron increases electron-electron repulsion in the outer shell, causing the size of the ion to increase.
- **Neutral Atom (I)**: The neutral iodine atom has a balanced number of protons and electrons. Its size is intermediate compared to the anion and cation.
- **Cation (I⁺)**: When iodine loses an electron, it becomes positively charged. The loss of an electron reduces electron-electron repulsion and allows the remaining electrons to be pulled closer to the nucleus, resulting in a smaller size.

### Step 3: Compare Sizes
Based on the above understanding:
- The size of the anion (I⁻) is the largest because it has gained an electron.
- The size of the neutral atom (I) is intermediate.
- The size of the cation (I⁺) is the smallest because it has lost an electron.

### Step 4: Write the Correct Order
Thus, the correct order of the size of iodine species from largest to smallest is:
**I⁻ > I > I⁺**

### Final Answer
The correct order of the size of iodine species is: **I⁻ > I > I⁺**

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