You're asking about the number of atoms in a *molecule* of sodium sulfide (Na₂S). Here's how to figure that out:

* The Formula: The chemical formula for sodium sulfide is Na₂S.

* Subscripts: The subscript "2" after the Na means there are two sodium atoms (Na) in each molecule.

* Total Atoms: There's one sulfur atom (S) in the molecule.

* Total: Therefore, there are a total of 3 atoms in a molecule of sodium sulfide (2 sodium + 1 sulfur).