Which of the following arrangements shows the correct order of electron affinity of the four halogen atoms I,Cl,Br,F?

Options

A. `I lt Br lt F lt Cl `
B. `Cl lt Br lt F gt I`
C. `Cl lt F lt Br lt I`
D. `F ~~I`` gt Br lt Cl `

Explanation

To determine the correct order of electron affinity for the halogen atoms (Iodine, Chlorine, Bromine, and Fluorine), we can follow these steps:

### Step 1: Understand Electron Affinity
Electron affinity is defined as the energy change that occurs when an electron is added to a neutral atom to form a negative ion. It is generally measured in kilojoules per mole (kJ/mol).

**Hint:** Remember that electron affinity is related to how easily an atom can accept an electron.

### Step 2: Analyze Trends in the Periodic Table
- **Down a Group:** As we move down a group in the periodic table (from Fluorine to Iodine), the atomic size increases. This is because additional electron shells are added, which increases the distance between the nucleus and the outermost electrons. Consequently, the effective nuclear charge felt by the incoming electron decreases, leading to a decrease in electron affinity.

**Hint:** Larger atoms have lower electron affinity due to increased distance from the nucleus.

- **Across a Period:** As we move across a period (from left to right), the atomic size decreases due to an increase in nuclear charge without a significant increase in shielding. This results in a higher effective nuclear charge, making it easier for the atom to attract and accept an additional electron, thus increasing electron affinity.

**Hint:** Smaller atoms generally have higher electron affinity due to stronger attraction to the nucleus.

### Step 3: Compare the Halogens
- **Fluorine (F):** Although it is the smallest halogen, it has a relatively low electron affinity compared to Chlorine due to electron-electron repulsion in its compact electron cloud.

- **Chlorine (Cl):** Chlorine has the highest electron affinity among the halogens because it is larger than Fluorine, allowing it to accommodate an additional electron more easily without significant repulsion.

- **Bromine (Br):** Bromine has a lower electron affinity than Chlorine and Fluorine because it is larger than both, leading to a weaker attraction for the incoming electron.

- **Iodine (I):** Iodine has the lowest electron affinity among the four halogens due to its larger atomic size and the corresponding decrease in effective nuclear charge.

### Step 4: Determine the Order
Based on the analysis:
- Chlorine (Cl) has the highest electron affinity.
- Fluorine (F) has a lower electron affinity than Chlorine but higher than Bromine.
- Bromine (Br) has a lower electron affinity than Fluorine.
- Iodine (I) has the lowest electron affinity.

Thus, the correct order of electron affinity for the halogens is:
**Cl > F > Br > I**

### Final Answer
The correct order of electron affinity for the halogens Iodine, Chlorine, Bromine, and Fluorine is:
**Cl > F > Br > I**

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