When the halogens form ionic compounds, what is the ion charge of the halide ions?
negative one
When halogens form ionic compounds, they typically gain one electron to achieve a stable, noble gas configuration. The noble gas configuration involves having a full outermost energy level, which is achieved by having eight valence electrons except for helium, which has two.
Since halogens have seven valence electrons, they will gain one electron to complete their outermost energy level and acquire a stable configuration. This results in the formation of negatively charged ions, known as halide ions. Therefore, the ion charge of the halide ions is -1.