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Why would our hands lose electrons easily?

  1. Dec 16, 2012 #1
    Our hands are high in the triboelectric series, which means our hands lose electrons easily. Is there a reason behind?
  2. jcsd
  3. Dec 17, 2012 #2


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    come on guys :wink:

    someone must be able to make an informed guess about this! :smile:
  4. Dec 17, 2012 #3
    The following is my conjecture based on a very brief examination of the triboelectric series table in the following link:

    “Triboelectric series

    Materials are often listed in order of the polarity of charge separation when they are touched with another object. A material towards the bottom of the series, when touched to a material near the top of the series, will attain a more negative charge, and vice versa. The further away two materials are from each other on the series, the greater the charge transferred. <The table is shown on the left>”

    The only proteins listed on the table are on top, among the materials that gain a positive charge. Skin is near the very top. Fur, silk and wool are located more to the middle. All these materials contain protein. There are no protein materials near the bottom, where materials gain a negative charge.

    Protein molecules are different from other organic in having an amine group attached to a carbon. I know from my courses in organic chemistry that the amine group has a tendency to donate molecules to any molecule that it is attached to.

    Therefore, I suggest one reason for skin being on the top of the series is that is contains a large concentration of proteins, leading to a high concentration of amine groups. When other materials are rubbed with proteins, a temporary chemical bond is formed with the amine group. The amine group tends to donate its electrons.

    Note that the triboelectric series continues to be unpredictable to a large extent. The speculation is an approximation limited to a very small class of molecules. I propose that protein molecules tend to be above the midline of the triboelectric series because of the amine group.

    While I am being silly, I just noticed something else.
    There are quite a few carbohydrates, alkenes and alkynes below the midline. For example, rayon is a carbohydrate. Vinyl and some of the other polymers have double bonds, making them alkenes.

    Carbohydrates contain hydroxyl groups. Alkenes and alkynes have multiple bonds.

    Hydroxyl groups in an organic molecule tend to accept electrons. Multiple bonds also tend to accept electrons.

    Maybe the hydroxyl groups and the multiple bonds tend to grab electrons, causing the negative charges at the bottom of the table.

    Some observations concerning the metals. I remember the following from my solid state courses. The majority free carrier in silver and gold are conduction electrons, which are negative. The majority free carrier in aluminum is the valence hole which is positive.

    Now I don't think that correlation is the same as cause. However, doesn't it seem interesting that aluminum acquires a positive charge while silver acquires a negative charge? Maybe holes can move into aluminum faster than electrons. Maybe conduction electrons can move into silver faster than holes. Maybe that is why aluminum is on top and silver near the bottom of the series.

    You should be warned that the triboelectric series is not always a transitive series. The hierarchy doesn't make an equivalence relation. Materials don't stay in one position of the group. So perceived correlations can be rather mystical.

    Pointy Haired Boss: As everyone says, correlation is cause >:-)
    Dilbert: Actually, no one says that ;-(
    Last edited: Dec 17, 2012
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