The correct name for Na2S is sodium sulfide.
The name is derived using the following rules for naming ionic compounds:
- Identify the cation and anion: In Na2S, Na is the cation (sodium) and S is the anion (sulfide).
- Name the cation: The cation, sodium (Na), is named directly from the element's name.
- Name the anion: The anion, sulfur (S), is modified to end with "-ide". Thus, sulfur becomes sulfide.
- Combine the names: The name of the compound is the name of the cation followed by the name of the anion. Therefore, Na2S is sodium sulfide.
