Draw to scale the three electron energy level and transition energy diagrams of the isolated neutral He atom (with two electrons) and the He+ lon (with on electron) in analogy to Figure (a)-(c) but taking into account the +2 nuclear charge from the two protons.
The first and second ionization potentials of He are 24.587eV and 54.416eV. There is again a solid-state analogy in semlconductors, such as the sulfur (valence=6) impurity center in silicon (valence=4).
