Which of the following has the highest electron affinity?

Options

A. `F`
B. `Br`
C. `CI`
D. `I`

Answer

To determine which of the following elements has the highest electron affinity, we need to follow these steps:

### Step 1: Understand Electron Affinity
Electron affinity refers to the amount of energy released when an electron is added to a neutral atom in the gas phase. A more negative value of electron gain enthalpy (ΔE) indicates a higher electron affinity.

### Step 2: Identify the Elements
Assuming we are comparing common elements such as fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), we need to analyze their electron affinities.

### Step 3: Analyze Electron Affinity Trends
- **Fluorine (F)**: Although it is the most electronegative element, its small atomic size leads to significant electron-electron repulsion when an additional electron is added. Thus, its electron affinity is not as negative as expected.
- **Chlorine (Cl)**: Chlorine has a larger atomic size compared to fluorine, which reduces the repulsion experienced by the added electron. Therefore, chlorine has a more negative electron gain enthalpy compared to fluorine.
- **Bromine (Br)** and **Iodine (I)**: These elements have even larger atomic sizes, leading to less effective nuclear charge felt by the added electron, resulting in less negative electron affinities compared to chlorine.

### Step 4: Conclusion
Among the halogens, chlorine has the most negative electron gain enthalpy, indicating that it has the highest electron affinity. Therefore, the answer is **Chlorine (Cl)**.

### Final Answer
**Chlorine (Cl) has the highest electron affinity among the given elements.**

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