Here's how to figure out the number of atoms in sodium sulfide (Na₂S):

* Chemical Formula: The formula Na₂S tells us there are 2 sodium (Na) atoms and 1 sulfur (S) atom in each molecule of sodium sulfide.

* Total Atoms: 2 (Na) + 1 (S) = 3 atoms

Therefore, there are 3 atoms in a molecule of sodium sulfide.