Final answer:
The electron configuration for the bromine anion (Br¹⁻) is [Ar]3d¹⁰ 4s² 4p⁶, which is the noble gas configuration of krypton.
Step-by-step explanation:
The electron configuration for the bromine anion (Br¹⁻) starts with the configuration of a neutral bromine atom and then adds one more electron to account for the extra negative charge of the anion. Bromine is in group 17 (halogens), and neutral bromine atoms have an atomic number of 35, which equates to 35 electrons. The electron configuration of a neutral bromine atom is [Ar]3d¹⁰ 4s² 4p⁵. When it gains an additional electron to form a Br¹⁻ ion, it achieves the same electron configuration as krypton (Kr), the next noble gas. Therefore, the electron configuration for the Br¹⁻ anion is [Ar]3d¹⁰ 4s² 4p⁶.