Final answer:
The term 'High Energy Level' refers to an electron's state that is above the least energetic state of an atom, with such levels akin to rungs on a ladder that get closer together as energy increases.
Step-by-step explanation:
The term 'High Energy Level' generally refers to the state of an electron in an atom that is above the atom's least energetic state.
As per the context provided, when a quantum number is increased by 1, an electron reaches a new, higher energy level, which signifies that it has greater energy. For example, if we increase the quantum number nx by 1, the corresponding energy state of the electron will rise.
Atoms and electrons, therefore, have energy levels analogous to rungs on a ladder, as expressed in Figure 9.4.4, where the rungs represent different states of energy that an electron can occupy. The spacing between these energy levels or 'rungs' becomes smaller at higher energies.
Materials like high-temperature superconductors demonstrate properties where electrons move through the material without losing energy, which is a concept closely tied to their energy levels and the behavior of atoms at different temperatures.