Show the filling of electron energy levels in Cu and Cu + . Please explain and show all work. Solution Electrons are filled in different sub-shell according to Aufbaus\'s rule(also called (n+l)rule ), Hunds rule and Pauli\'s exclusion principle Electronic configuration of Cu(Z=29) is 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10 (instead of 4s 2 3d 9 since 4s 1 3d 10 is a more stable configuration i.e. fully filled d-subshell and half-filled s-subshell with more exchange energy) During formation of Cu + , one electron is to be removed. Since 4s is the outer sub-shell and 3d is the penultimate subshell, electron is removed from 4s instead of 3d. This means although 4s (4+0=4, n+l rule) is filled before 3d(3+2=5, n+l rule) but removal of electron takes place from outermost orbital. Electronic configuration of Cu + is 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 .

1. Show the filling of electron energy levels in Cu and Cu +
. Please explain and show all work.
Solution
Electrons are filled in different sub-shell according to Aufbaus's rule(also called (n+l)rule ),
Hunds rule and Pauli's exclusion principle
Electronic configuration of Cu(Z=29) is 1s 2
2s 2
2p 6
3s 2
3p 6
4s 1
3d 10
(instead of 4s 2
3d 9
since
4s 1
3d 10
is a more stable configuration i.e. fully filled d-subshell and half-filled s-subshell with
more exchange energy)
During formation of Cu +
, one electron is to be removed. Since 4s is the outer sub-shell and 3d is
the penultimate subshell, electron is removed from 4s instead of 3d. This means although 4s
(4+0=4, n+l rule) is filled before 3d(3+2=5, n+l rule) but removal of electron takes place from
outermost orbital.
Electronic configuration of Cu +
is 1s 2
2s 2
2p 6
3s 2
3p 6
3d 10