* Sodium (Na) is a metal and tends to lose one electron to achieve a stable electron configuration, forming a +1 cation (Na⁺).
* Sulfur (S) is a nonmetal and tends to gain two electrons to achieve a stable electron configuration, forming a -2 anion (S⁻²).
To form a neutral compound, the charges must balance. This means two sodium ions (2Na⁺) are needed to combine with one sulfide ion (S⁻²) resulting in the ionic compound sodium sulfide (Na₂S).
