5.1. Light http://www.ck12.org
FIGURE 5.8
When light from a hydrogen gas discharge tube is passed through a prism, the light is split into four visible lines.
Each of these spectral lines corresponds to a different electron transition from a higher energy state to a lower
energy state. Every element has a unique atomic emission spectrum. The emission spectra for helium (He) and
iron (Fe) are also shown.has its own unique atomic emission spectrum that can be used to determine the identity of an unknown gas. This
technique is used extensively in astronomy to identify the composition of distant stars.
As in the case of the photoelectric effect, classical theories were unable to explain the existence of atomic emission
spectra, also known as line-emission spectra. According to classical physics, a ground state atom would be able