What is the electron configuration of the sulfide ion (S²⁻)?

To determine the electron configuration of the sulfide ion (S²⁻), it is essential to first understand the basic configuration of a neutral sulfur atom. Sulfur has an atomic number of 16, meaning it has 16 electrons in its neutral state. The electron configuration for a neutral sulfur atom is written as 1s² 2s² 2p⁶ 3s² 3p⁴.

However, the sulfide ion represents sulfur that has gained two additional electrons, resulting in a total of 18 electrons. To accommodate this increase in electrons, the two additional electrons will fill the next available subshells. After the 3p subshell, the next subshell is the 3p, which can hold up to 6 electrons. By adding these two extra electrons to the sulfur atom's configuration, the configuration of the sulfide ion becomes 1s² 2s² 2p⁶ 3s² 3p⁶.

This configuration is identical to that of the nearest noble gas, argon, indicating that the sulfide ion has achieved a stable electronic arrangement by filling up the 3p subshell completely. Thus, the full electron configuration for S²⁻