The ionic compound formed by Cesium (Cs) and Oxygen (O) is Cesium Oxide, with the formula Cs₂O. Here's how to determine that:

* Cesium (Cs) is in Group 1 of the periodic table, meaning it has a +1 charge as a cation (Cs⁺).

* Oxygen (O) is in Group 16, meaning it has a -2 charge as an anion (O²⁻).

To balance the charges and create a neutral compound, we need two Cesium ions (+1 each) for every one Oxygen ion (-2):

* 2(Cs⁺) + 1(O²⁻) = 0

Therefore, the formula for Cesium Oxide is Cs₂O.