Number of valence electrons in `Cl^(– )` ion are:

Options

A. 16
B. 8
C. 17
D. 18

Explanation

To determine the number of valence electrons in the `Cl^(-)` ion, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Atomic Number of Chlorine (Cl)**:
- Chlorine has an atomic number of 17. This means it has 17 electrons.

2. **Determine the Electronic Configuration of Chlorine**:
- The electronic configuration of chlorine can be written as:
\[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^5 \]
- In a simplified form, this can be represented as:
\[ 2, 8, 7 \]
- Here, the numbers represent the distribution of electrons in the shells: 2 electrons in the first shell, 8 in the second shell, and 7 in the third shell.

3. **Understand the Formation of the `Cl^(-)` Ion**:
- The `Cl^(-)` ion indicates that chlorine has gained one additional electron.
- When chlorine gains one electron, it becomes negatively charged (`Cl^(-)`).

4. **Determine the New Electronic Configuration of `Cl^(-)`**:
- After gaining one electron, the electronic configuration of `Cl^(-)` becomes:
\[ 2, 8, 8 \]
- This means there are now 8 electrons in the outermost shell (the third shell).

5. **Identify the Valence Electrons**:
- The valence electrons are the electrons present in the outermost shell.
- For `Cl^(-)`, the outermost shell (M shell) has 8 electrons.

6. **Conclusion**:
- Therefore, the number of valence electrons in the `Cl^(-)` ion is **8**.

### Final Answer:
The number of valence electrons in the `Cl^(-)` ion is **8**.