Write the electron configuration for each ion. b. Br^-

Electron configuration describes the distribution of electrons in an atom or ion's orbitals. It is represented using a notation that indicates the energy levels and sublevels occupied by electrons. For example, the electron configuration of a neutral bromine atom (Br) is 1s² 2s² 2p⁶ 3s² 3p⁵, which shows how electrons are arranged in various energy levels.

Ionic charge refers to the electrical charge that an atom or ion carries due to the loss or gain of electrons. Anions, like Br⁻, are negatively charged ions formed when an atom gains one or more electrons. This additional electron alters the electron configuration, resulting in a more stable arrangement, often resembling that of the nearest noble gas.

Noble gas configuration is a shorthand notation for electron configurations that highlights the stability of noble gases, which have full outer electron shells. For bromine, gaining an electron to form Br⁻ results in the electron configuration of krypton (Kr), the nearest noble gas, which is 1s² 2s² 2p⁶ 3s² 3p⁶. This configuration indicates that Br⁻ has achieved a stable electronic state.