Why does helium not form `He_2`, like `Cl_2` molecule ? 

Explanation

### Step-by-Step Solution:

1. **Understanding the Nature of Helium and Chlorine:**
- Helium (He) is a noble gas with a complete outer electron shell (1s²), making it very stable and inert.
- Chlorine (Cl), on the other hand, has an incomplete outer shell (3s² 3p⁵) and can easily form bonds with another chlorine atom to achieve a stable electron configuration (Cl₂).

2. **Electron Configuration of Helium:**
- The electron configuration of helium is 1s², meaning it has two electrons in its outermost shell. This configuration is already stable and does not require additional electrons to achieve stability.
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