## Chemistry: Molecular Approach (4th Edition)

a. $O^{2-} = 1s^{2} 2s^{2} 2p^{6}$ b. $Br^{-} = [Ar] 4s^{2} 3d^{10} 4p^{6}$ c. $Sr^{2+} = [Ar] 4s^{2} 3d^{10} 4p^{6}$ d. $Co^{3+} = [Ar] 3d^{6}$ e. $Cu^{2+} = [Ar] 3d^{9}$ Note: b and c are just the configuration of [Kr].