To determine the number of atoms in Ca(NO3)2, we need to consider the individual atoms present in the compound.

Calcium nitrate, Ca(NO3)2, consists of the following atoms:

- 1 Calcium (Ca) atom

- 2 Nitrogen (N) atoms

- 6 Oxygen (O) atoms

So, the total number of atoms in Ca(NO3)2 is:

1 Ca atom + 2 N atoms + 6 O atoms = 1 + 2 + 6 = 9 atoms

Therefore, there are a total of 9 atoms in one molecule of Ca(NO3)2.