The number of valence shell electrons of the most electronegative element is _________.

Explanation

To determine the number of valence shell electrons of the most electronegative element, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Most Electronegative Element:**
- The most electronegative element in the periodic table is Fluorine (F). Its electronegativity value is 4.0.

2. **Understand Valence Shell Electrons:**
- Valence shell electrons are the electrons present in the outermost shell of an atom. These electrons are important for determining how an element will react chemically.

3. **Determine the Atomic Number and Electronic Configuration of Fluorine:**
- Fluorine has an atomic number of 9. Its electronic configuration is:
- 1s² 2s² 2p⁵.

4. **Count the Valence Electrons:**
- The valence electrons are found in the outermost shell (the second shell for Fluorine). In the case of Fluorine:
- The 2s subshell has 2 electrons (2s²).
- The 2p subshell has 5 electrons (2p⁵).
- Therefore, the total number of valence electrons in Fluorine is:
- 2 (from 2s) + 5 (from 2p) = 7 valence electrons.

5. **Conclusion:**
- The number of valence shell electrons of the most electronegative element, Fluorine, is **7**.

### Final Answer:
The number of valence shell electrons of the most electronegative element is **7**.

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