Answer
See the detailed answer below.
Work Step by Step
$\bullet$ The Ground-State Electron Configuration of Potassium (K, $ Z = 19 $) is:
$$
1s^2 2s^2 2p^6 3s^2 3p^6 4s^1
$$
This indicates that all the states up to the $ 4s $ orbital are completely filled, except for the $ 4s $ state, which has only one electron.
$\bullet$ The Ground-State Electron Configuration of Scandium (Sc, $ Z = 21 $) is:
$$
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^1
$$
All the states up to the $ 4s $ state are filled, but it also has electrons in the $ 3d $ subshell. The $ 3d $ subshell contains a single electron in this case.
$\bullet$ The Ground-State Electron Configuration of Copper (Cu, $ Z = 29 $) is:
$$
1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^{10}
$$
Copper is an exception to the typical filling order. It prefers a completely filled $ 3d $ subshell (with 10 electrons) and has only a single electron in the $ 4s $ state. This configuration reflects the stability gained from having a fully filled $ 3d $ subshell.
$\bullet$ The Ground-State Electron Configuration of Germanium (Ge, $ Z = 32 $) is:
$$
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^2
$$
For germanium, the ground-state electron configuration includes completely filled $ 4s $ and $ 3d $ subshells and partially filled $ 4p $ subshell. This configuration shows that germanium has two electrons in the $ 4p $ subshell, while the $ 4s $ and $ 3d $ subshells are completely filled.
These electron configurations demonstrate the filling of orbitals in a systematic manner based on the energy levels and the stability of fully or half-filled subshell.
See the 4 figures below.
