Emission and absorption spectrum
“Why do elements absorb light?”
Light is something that we literally see everyday, whether it be from the sun shining down on civilization during the day, the incandescent light bulbs lighting up our night, or the flashlights we use to read in bed. However, as light is both a wave and a particle, it has to interact with material objects when it makes contact, so what happens when it does so? Well, let’s think about it. We know that light is composed of atomic-size forms of matter known as photons, and we also know that as a result of the wave-particle dualistic nature of light, these photons will have a wavelength associated with them. And since light is emitted by radiation, these photons will have a distributions of multiple wavelengths, all of which have a corresponding energy. Furthermore, all material objects are comprised of atoms, which have discrete energy levels. So when a photon wave hits a material object, the atom can only absorb the photon if it corresponds to the precise energy level. This energy level will stay elevated for a limited amount of time, and will soon fall back down to the original energy level, emitting a wave of the same energy level. If one were to take an empirical measurement of the wavelengths being emitted by constructing an emission and absorption spectrum, then one would be able to identify the element present!