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B Photoelectric effect

  1. Apr 22, 2016 #1
    Guys I'm understand this effect but understanding it i got a practical doubt that though the bond(metallic bond) between metal atoms is very strong then too electrons are easily ripped of compared to other elements
    I know metals have free electrons but they are strongly bonded to the atoms then how its happening? Please explain. Thankyou
     
  2. jcsd
  3. Apr 22, 2016 #2

    mfb

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    Some electrons are bound to atoms, others (those that form the metallic bonds) are not. The electrons with the most energy are not tightly bound to the metal.
     
  4. Apr 22, 2016 #3
    How you can explain it because as per you the more energy electrons are not tightly bonded but they contibute to the strongest bonding in metal elements?
     
  5. Apr 22, 2016 #4

    mfb

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    There are different electron energy levels. The deeper ones contribute more to keeping the metal together, the higher ones are easier to remove from the metal. In total, the large number of electrons that contribute to the binding energy are relevant as well. Not that much energy per electron, but many electrons.
     
  6. Apr 23, 2016 #5
    But still I'm not satisfied by the fact that the electrons that are left by metal for strong metallic bonding are easily ripped off. I'm thinking in a view that these electrons are major contributors to bonding.
     
  7. Apr 23, 2016 #6

    mfb

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    They are not.

    Also, what are the comparisons you seem to imply? Easy/hard compared to what?
     
  8. Apr 23, 2016 #7
    There are tons of electrons around a metal because of its high atomic number. Some of these electrons don't interact much with anything but its own atoms protons. Some are jumping back and forth and playing with its neighbors atom.

    Some electrons roam around its atom pretty freely and can be repelled by other electrons and be pushed farther down the metal until it replaces another electrons spot.
     
  9. Apr 23, 2016 #8
    Whoops that explanation was for current in a wire and not the photoelectric effect but it should be fine.

    I want to ask how a photon transfers its energy to an electron but I'm sure you guys would get mad at me.
     
    Last edited: Apr 23, 2016
  10. Apr 24, 2016 #9
    You should look up the values before assuming some relationship (like it is easier or harder).
    If you take sodium as an example, the binding energy per atom is 1.1 eV (according to the table in Kittel).
    The work function for sodium is about 2.3 eV.
    So, do you think that these numbers justify your claim that is "too easy" to extract free electrons from the metal?
     
  11. Apr 25, 2016 #10

    sophiecentaur

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    Typically, a few eV, for the outer electrons and that is the sort of energy that's needed to break individual electrons free form the surface. The strength of a solid metal is due to the very large number of these small forces.
     
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