All Right Cesium is an Alkali Metal so it Belongs to the first Column of the Periodic table. Every Element in that Column Has a Charge of 1+ as a cation. so at the answer your question, a single Cesium atom loses 1 electron when it became cation. This cation look like this:
cs=55 electrons
cs^+= 54 Electrons
As you Can see it only loses one
