What principle explains the atomic emission spectrum?

The atomic emission spectrum is fundamentally linked to the behavior of electrons in an atom. When electrons in an atom absorb energy, they can move from their original energy level to a higher energy level, indicating that they have been excited. However, this state is not stable, and the electrons will eventually return to a lower energy level. As they transition back down to these lower energy levels, they release energy in the form of light.

This emitted light appears as distinct wavelengths, which correspond to specific colors, and collectively, these wavelengths form the emission spectrum unique to that element. Each element has a unique set of energy levels, thus producing a characteristic emission spectrum. The principle of this phenomenon is best captured by the understanding that the emission of light occurs specifically during the transition of electrons from a higher energy state to a lower energy state.

The other options do not accurately represent the principles involving atomic emission. For instance, while it is true that electrons gain energy to move to higher energy levels, that process does not directly explain the emission spectrum itself, but rather the initial step before emission occurs. The mention of collisions with other atoms or nuclear splitting introduces unrelated concepts that do not pertain to the emission spectra of individual atoms. Thus, the correct statement precisely captures the