Origin of Color
Since atoms are colorless, where do all the colors come from?
Materials interact with light in different ways, causing your eye to see
different colors. Atoms do absorb light, and so it is not exactly true that
atoms are colorless. You would be hard-pressed to 'see' a single atom or its
color, but when you group them together, you can see them and their color.
As an analogy, it is hard to see a single particle of dust, but when it
builds up into dust-bunnies, you sure can see it! Atoms are the same way --
if there is not many of them, they are very hard to see, but when you get
enough of them, you can see them.
Although pure elements (an 'element' is a material made of a single type of
atom) can have color, the bright vivid colors of nature are usually chemical
compounds made of different types of atoms. Chemical bonds -- groups of
atoms arranged in just the right way -- will strongly absorb certain
wavelengths of light, but not others. Since white light is a mixture of all
the colors, if a material absorbs the red and green light, it will appear
blue to you. Many famous pigments (like the green color of chlorophyll, the
green component in plants), absorb light due to their special arrangements
of chemical bonds. Other materials -- colorful minerals like gemstones come
to mind -- absorb light due to impurities in their crystal structure (when
you substitute a different atom into the crystal instead of the usual one,
the crystal will change slightly, and its color will change too). Generally,
though, the color you see is due to the material absorbing some of the
light, but not all. The light that is not absorbed is the color you see.
Hope this helps,
Click here to return to the Physics Archives
Update: June 2012