Why does an absorption spectrum look the way it does?

An absorption spectrum appears as a series of dark lines or bands superimposed on a continuous spectrum of light. This occurs when a substance absorbs specific wavelengths of light, corresponding to the energy levels of its electrons. The absorbed wavelengths result in the absence of light at those specific frequencies, creating the characteristic dark lines. Each element has a unique set of energy levels, leading to a distinct absorption spectrum that can be used for identification.