* The Formula: Calcium chloride has the formula CaCl₂. This means each formula unit contains one calcium atom (Ca) and two chlorine atoms (Cl).

* Two Formula Units: Since we have two formula units, we double the number of chlorine atoms: 2 formula units * 2 Cl atoms/formula unit = 4 chlorine atoms

Therefore, there are 4 chlorine atoms in two calcium chloride formula units.