Which halogen has the tendency to form cations?

Explanation

To determine which halogen has the tendency to form cations, we can analyze the properties of the halogen group, which includes fluorine, chlorine, bromine, and iodine.

### Step-by-Step Solution:

1. **Identify the Halogens**: The halogens are a group of elements in Group 17 of the periodic table, which includes fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

2. **Understand the Trend in the Group**: As we move down the group from fluorine to iodine, several trends can be observed:
- The atomic size increases.
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