To determine which of the given species has the lowest number of electrons in the valence shell, we will analyze each option step by step.
### Step 1: Analyze O²⁻ (Oxide Ion)
- The atomic number of oxygen (O) is 8.
- The neutral oxygen atom has 8 electrons, arranged as 2 in the first shell and 6 in the second shell (valence shell).
- When it gains 2 electrons to form O²⁻, it has a total of 10 electrons.
- The electron configuration becomes 2 (first shell) + 8 (second shell).
- Therefore, in the valence shell (the outermost shell), there are **8 electrons**.
### Step 2: Analyze S (Sulfur)
- The atomic number of sulfur (S) is 16.
- A neutral sulfur atom has 16 electrons, arranged as 2 in the first shell, 8 in the second shell, and 6 in the third shell (valence shell).
- Therefore, in the valence shell of sulfur, there are **6 electrons**.
### Step 3: Analyze N³⁻ (Nitride Ion)
- The atomic number of nitrogen (N) is 7.
- A neutral nitrogen atom has 7 electrons, arranged as 2 in the first shell and 5 in the second shell (valence shell).
- When it gains 3 electrons to form N³⁻, it has a total of 10 electrons.
- The electron configuration becomes 2 (first shell) + 8 (second shell).
- Therefore, in the valence shell, there are **8 electrons**.
### Step 4: Analyze Cl⁻ (Chloride Ion)
- The atomic number of chlorine (Cl) is 17.
- A neutral chlorine atom has 17 electrons, arranged as 2 in the first shell, 8 in the second shell, and 7 in the third shell (valence shell).
- When it gains 1 electron to form Cl⁻, it has a total of 18 electrons.
- The electron configuration becomes 2 (first shell) + 8 (second shell) + 8 (third shell).
- Therefore, in the valence shell, there are **8 electrons**.
### Conclusion
Now, we summarize the number of electrons in the valence shell for each species:
- O²⁻: 8 electrons
- S: 6 electrons
- N³⁻: 8 electrons
- Cl⁻: 8 electrons
The species with the lowest number of electrons in the valence shell is **sulfur (S)**, which has **6 electrons**.
### Final Answer
The species with the lowest number of electrons in the valence shell is **sulfur (S)**.
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