5.1 Atomic Spectra

When atoms and electrons are energetically excited, for example through irradiation with light of a specific energy, atoms can absorb and emit light (their spectrum). Each atom has a distinct spectrum of colours it emits. It's these spectra that give fireworks its different colours by adding different metal atoms to the firework.

The Energy of Light

In Module 2. Physical Chemistry, we discussed how electrons in an atom exist in orbitals of discrete energy. This is directly evident when observing atomic spectra. First, remember that the electromagnetic spectrum is the range of frequencies that electromagnetic radiation or light can have. Also, the frequency of light corresponds to the photon’s (a light particle) energy. The higher the frequency of the photonA particle of light. It is the particle which explains the particle-wave duality of light. It has no mass and it’s speed is the speed of light 3.00 × 10⁸ m/s (in vacuum). It is the primary energy carrier of light. The energy of a photon is dependent on the frequency., the higher its energy.