The landing at the bottom of the staircase is like the lowest energy level in an atom. Each step up represents a higher energy level. The distance between two steps represents the difference in energy between two energy levels. To continue the analogy, there would need to be a different staircase for each element because no two elements have the same set of energy levels.

An electron in an atom can move from one energy level to another when the atom gains or loses energy. An electron may move up two energy levels if it gains the right amount of energy. An electron in a higher energy level may move down two energy levels if it loses the right amount of energy. The size of the jump between energy levels determines the amount of energy gained or lost.

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