Write the number of atoms of each element found in one unit of the compound:

Potassium iodide, KI

Sodium sulfide, Na2S

Silicon Dioxide, SiO2

Carbonic acid, H2CO3

The number of atoms of each element found in one unit of the compound:

Potassium iodide, KI, one atom K, one atom I

Sodium sulfide, Na2S, two atoms Na, 1 atom S

Silicon Dioxide, SiO2, one atom Si, two atoms O

Carbonic acid, H2CO3, two atoms H, 3 atoms O