Halogens have high electron gain enthalpies because the addition of an electron gives them the........configuration

Explanation

To solve the question, "Halogens have high electron gain enthalpies because the addition of an electron gives them the ______ configuration," we need to understand a few concepts related to halogens and electron gain enthalpy.

### Step-by-Step Solution:

1. **Understanding Electron Gain Enthalpy**:
- Electron gain enthalpy refers to the amount of energy released when an electron is added to a neutral atom in the gaseous state. For halogens, this process is highly exothermic, meaning a significant amount of energy is released.

**Hint**: Remember that halogens are located in Group 17 of the periodic table and have seven valence electrons.
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