Ionic Compound Naming: Cs2S

When looking at the formula Cs2S, we can see that the compound consists of cesium (Cs) and sulfur (S) ions. Cesium is a metal element with atomic number 55, while sulfur is a non-metal with atomic number 16. These elements combine to form an ionic compound due to their opposite charges.

Cesium is a group 1 metal and forms a +1 cation, denoted as Cs+. Sulfur, on the other hand, is a group 16 non-metal and forms a -2 anion, denoted as S2-. When cesium and sulfur ions combine in a 2:1 ratio, they form the ionic compound Cs2S.

The cesium cations (Cs+) balance out the charge of the sulfur anions (S2-) to create a neutral compound. This compound follows the rules of ionic compound naming, where the metal cation is named first followed by the non-metal anion with an "-ide" ending.

Therefore, the ionic compound Cs2S is named cesium sulfide, with the cesium cations neutralizing the charge of the sulfur anions. Understanding the elements present in an ionic compound and their charges is crucial in naming and predicting the properties of these compounds.