- Things appear to have colour because they absorb some wavelengths of light and reflect others.
- Chromophores are the part of molecules responsible for the absorption and reflection of light.
- A chromophore is formed by a group of atoms within a molecule and the electrons that orbit their nuclei.
- The colour produced by an opaque object corresponds with the wavelengths not absorbed during the interaction of light with the chromophores of the molecules that form its surface.
- Whether different wavelengths of light are absorbed or reflected by a chromophore depends on whether there is an energy difference between orbiting electrons.
- If the energy difference between the electrons of a chromophore falls within the range of the visible spectrum (2 to 2.75 electron volts) then it produces the colour seen by an observer.