What is the electron configuration of br, z=35?

The electron configuration of Bromine or Br with z=35, we have to obtain 35e-. The answer is furthered to:
1.       The expanded electron configuration is 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p5.

2.       While with the noble gas, which was extracted from Bromine’s expanded electron configuration staring from 1s2 to 3p6. Please refer above. It is the electron configuration of Argon, so we write [Ar] with the brackets then copy the remaining, 4s2, 3d10, 4p5. Hence, in simplified form is [Ar] 4s2, 3d10, 4p5.

Determine the  wavelength of light emitted when an electron  in an li2+ ion  makes a transition from an orbital with n  =  6 to an orbital with n  = 5.