Ammonium oxide, also known as diammonium oxide, has the formula (NH₄)₂O. Here's how to break down the number of atoms:

* Nitrogen (N): There are two nitrogen atoms (from the two NH₄ groups).

* Hydrogen (H): There are eight hydrogen atoms (2 NH₄ groups x 4 hydrogen atoms each).

* Oxygen (O): There is one oxygen atom.

Therefore, ammonium oxide has a total of 11 atoms.