Which halogen has highest ionisation potential

Options

A. Fluorine
B. Chlorine
C. Bromine
D. Iodine

Answer

To determine which halogen has the highest ionization potential, we can follow these steps:

### Step 1: Understand Ionization Potential
Ionization potential (or ionization energy) is the minimum amount of energy required to remove the most loosely bound electron from an isolated gaseous atom of an element.

### Step 2: Identify the Halogens
The halogens in question are:
- Fluorine (F)
- Chlorine (Cl)
- Bromine (Br)
- Iodine (I)

### Step 3: Analyze the Trend in Ionization Potential
Ionization potential generally increases across a period from left to right and decreases down a group in the periodic table.

### Step 4: Apply the Trend to Halogens
As we move down the group of halogens (from fluorine to iodine), the atomic size increases. This increase in size means that the outermost electrons are further from the nucleus, which results in a weaker nuclear attraction on these electrons. Consequently, it requires less energy to remove an electron as we go down the group.

### Step 5: Compare the Halogens
- **Fluorine** has the smallest atomic size among the halogens listed, meaning its outer electrons are closer to the nucleus and experience a stronger nuclear attraction.
- **Chlorine**, **Bromine**, and **Iodine** have larger atomic sizes, resulting in lower ionization potentials compared to fluorine.

### Step 6: Conclusion
From the analysis, we conclude that **Fluorine (F)** has the highest ionization potential among the halogens.

### Final Answer
The halogen with the highest ionization potential is **Fluorine (F)**.

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