Final answer:
A line spectrum is the emission of light at discrete wavelengths by an excited atom, each line representing a specific transition between energy levels within the atom, rather than a continuous range of wavelengths.
Step-by-step explanation:
The term you're looking for is “line spectrum”, which describes the emission of light by excited state atoms consisting of a series of discrete bands, or lines, at specific wavelengths, rather than a continuous range. This phenomenon is part of electromagnetic radiation and is a unique characteristic of the atomic structure of each element. When an atom's electron moves from a higher energy level to a lower one, it emits energy in the form of light and produces a line spectrum. Each emitted light corresponds to a single wavelength that is characteristic of the transition between specific energy levels in the atom.
As an example, the hydrogen atom shows a line spectrum when it is excited, such as by an electric discharge. The emitted light, after being passed through a prism, reveals discrete wavelengths, which are observed as lines and are known as the Balmer series transitions in the visible spectrum. Similar behavior is observed in other elements, with each element having its own unique line spectrum.