Which one of the following has the smallest size ?

Options

A. AI
B. `AI^(+)`
C. `AI^(+2)`
D. `AI^(+3)`

Explanation

To determine which element has the smallest size among a given set, we need to understand the concepts of atomic size, cations, anions, and neutral atoms. Here’s a step-by-step solution:

### Step 1: Understand Atomic Size
Atomic size refers to the distance from the nucleus of an atom to the outermost shell of electrons. The size of an atom can vary based on its charge state.

**Hint:** Remember that atomic size is influenced by the number of electrons and protons in an atom.

### Step 2: Differentiate Between Cations, Anions, and Neutral Atoms
- **Cations** are positively charged ions formed when an atom loses one or more electrons. They are smaller than their neutral atoms because the loss of electrons reduces electron-electron repulsion in the outer shell.
- **Anions** are negatively charged ions formed when an atom gains one or more electrons. They are larger than their neutral atoms because the addition of electrons increases electron-electron repulsion.
- **Neutral Atoms** have no charge and are in between the sizes of cations and anions.

**Hint:** Cations are smaller than neutral atoms, and anions are larger than neutral atoms.

### Step 3: Compare the Sizes
When comparing sizes:
- The more positive charge a cation has, the smaller its size will be.
- The more negative charge an anion has, the larger its size will be.

**Hint:** Focus on the charge of the ions when comparing their sizes.

### Step 4: Analyze the Given Elements
If you have a set of elements such as Al, Al⁺, Al²⁺, and Al³⁺:
- Al (neutral) has a certain size.
- Al⁺ (loses one electron) is smaller than Al.
- Al²⁺ (loses two electrons) is smaller than Al⁺.
- Al³⁺ (loses three electrons) is the smallest because it has lost the most electrons.

**Hint:** The trend shows that as the positive charge increases, the size decreases.

### Step 5: Conclusion
Based on the analysis, Al³⁺ will have the smallest size among the given options.

**Final Answer:** Al³⁺ has the smallest size.

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