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What is color?

  1. Feb 13, 2004 #1
    Hey guys

    Something in my microbiology class today got me thinking.

    What is color? I mean, I'm writing this on my laptop computer, and the area around my keyboard is blue. But why is it blue? I know that it is plastic that is dyed blue, so there exists some type of blue pigment on the plastic, but I don't understand what makes a pigment blue.

    I mean, at a basic level, everything is just atoms, right? What is it about a certain group of atoms that gives it a particular color?

    I figure it has to do something about which wavelenghts of light it absorbs and which ones it reflects, but any more than that I don't understand or have knowledge of.

    Thank you
  2. jcsd
  3. Feb 13, 2004 #2
    your desk is blue because thats mainly the only colour it doesnt absorb. meaning the blue colour gets reflected to your eye.
  4. Feb 13, 2004 #3


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    And to be even more specific, a particular substance will absorb light if the atoms in the substance have an electron energy level available near the photon's energy, or if the molecules have a vibrational or rotational mode available near the photon's energy.

    The constituent atoms, and the way they are connected in molecules, determines which colors of light a substance can absorb.

    - Warren
  5. Feb 13, 2004 #4
    Is there any relation to an elements color and its position in the periodic table, across the rows of the different quantum levels?

    Like the example they give for the excited state of an atom, when it absorbs a wavelength of light and it excites an electron to jump up a quantum level, since the atom absorbs that wavelength of light, would that give the atom a color because of the absence of that particular wavelength of light throughout the visible spectrum?
  6. Feb 14, 2004 #5


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    Not in the sense that you mean it. There is a relationship between the make up of an atom and the and the color of the flame when an element is burned, but when "absorbing and re-emitting" a photon the color of the absorbed and emitted photon will be the same.

    Additionally, "metals"- those elements with a lot of "loose" electrons will appear shiny.
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