1. Start with the neutral sulfur atom:
* Sulfur (S) has an atomic number of 16, meaning it has 16 protons and 16 electrons.
* The ground-state electron configuration of sulfur is: 1s² 2s² 2p⁶ 3s² 3p⁴
2. Add the extra electrons for the sulfide ion:
* The sulfide ion (S²⁻) has gained two extra electrons to achieve a stable octet.
* Adding two electrons to the 3p subshell gives us the final configuration: 1s² 2s² 2p⁶ 3s² 3p⁶
Therefore, the ground-state electron configuration of the sulfide ion (S²⁻) is 1s² 2s² 2p⁶ 3s² 3p⁶.
