The charge on the cesium ion is +1. This is because cesium (Cs) is an alkali metal, which means it has one electron in its outermost shell. In order to achieve a stable electron configuration, cesium tends to lose this single electron, resulting in a positively charged ion with a charge of +1.
When cesium loses its outermost electron, it forms a cesium ion, denoted as Cs+. This ion has a full outer shell of electrons, making it more stable than the neutral cesium atom. The +1 charge indicates that the cesium ion has one more proton than electrons, giving it a net positive charge.
This behavior is typical of alkali metals, which all have a single electron in their outermost shell and tend to form +1 ions by losing that electron.