Bromine.
The electron configuration for Cu using spdf notation is 1s2 2s2 2p6 3s2 3p6 3d10 4s1 4p6.
The complete electron configuration for the chromium(III) ion is 1s22s22p63s23p64s03d3.
Group 2 (Alkaline Earth Metals) Beryllium: 1s2 2s2 Magnesium: 1s2 2s2 2p6 3s2 Calcium: 1s2 2s2 2p6 3s2 3p6 4s2 Strontium: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2 Barium: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2 4d10 5p6 6s2 Radium: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4f14 4d10 4p6 5s2 5d10 5p6 6s2 6s2 6p6 7s2
2, 8, 18, 3[Ar] 4s2 3d10 4p1[1s2, 2s2 2p6, 3s2 3p6] 4s2, 3d10, 4p1
It is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6.
1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d10 or [Ar]3d10, 4s1
The electron configuration for Cu using spdf notation is 1s2 2s2 2p6 3s2 3p6 3d10 4s1 4p6.
The complete electron configuration for the chromium(III) ion is 1s22s22p63s23p64s03d3.
Group 2 (Alkaline Earth Metals) Beryllium: 1s2 2s2 Magnesium: 1s2 2s2 2p6 3s2 Calcium: 1s2 2s2 2p6 3s2 3p6 4s2 Strontium: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2 Barium: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2 4d10 5p6 6s2 Radium: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4f14 4d10 4p6 5s2 5d10 5p6 6s2 6s2 6p6 7s2
2, 8, 18, 3[Ar] 4s2 3d10 4p1[1s2, 2s2 2p6, 3s2 3p6] 4s2, 3d10, 4p1
It is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6.
That is Arsenic.
1s2 2s2 2p6 3s2 3p6 4s2 3d10
Bromine
The electron configuration of Mg is 1s2 2s2 2p6 3s2. For SO4^2-, the electron configuration is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6. MgSO4 consists of one Mg atom and one SO4^2- ion, so the overall electron configuration would be Mg: 1s2 2s2 2p6 3s2 and SO4^2-: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6.
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 or [Kr] 5s1
Rubidium (Rb)