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Size of atoms.

  1. Mar 12, 2006 #1
    Does anyone know how to prove that the size of atoms is nearly 10^-8cm?:uhh:
    Thank you
  2. jcsd
  3. Mar 12, 2006 #2
    I'd calculate the expectation value of r for the outmost electrons. That should give a ballpark estimate.
  4. Mar 12, 2006 #3


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    Staff Emeritus
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    Copper (for instance) is a close-packed metal. From its density and atomic mass you can calculate the distance between the centers of neighboring atoms. This will be nothing but twice the radius of the copper atom.
  5. Mar 13, 2006 #4
    I understood what you mean but I still don't know how to calculate it.:rolleyes:
  6. Mar 13, 2006 #5


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    First, many atoms, heavy ones, are much bigger than 10-8 cm.

    Second. Read any discussion of the quantum theory of the hydrogen atom and you, with perhaps a bit of work, will find your answer,/
    Reilly Atkinson
  7. Mar 13, 2006 #6


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    Staff: Mentor

    Copper has a density of 8.92 g/cm^3. It has an atomic mass of 63.5, which means that 63.5 g of copper contains 6.02 x 10^23 atoms (one mole). Using these numbers, you can find the volume (cm^3) per atom just by analyzing the units and doing a little arithmetic. Try it! :smile:
  8. Mar 13, 2006 #7
    Your suggestions were really helpfull, thank you all.:smile:
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