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If an Atom was the size of a grain of salt

  1. Feb 20, 2012 #1
    What object would represent the size of a grain of salt at this scale?

    Would it be bigger than Earth?
     
  2. jcsd
  3. Feb 20, 2012 #2

    Mark44

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    Is this a homework problem?

    What are your thoughts on your problem?
     
  4. Feb 20, 2012 #3

    Ryan_m_b

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    The smallest atom is helium at ~30pm, a very large atom like caesium is ~225pm. Salt obviously varies in size but let's say it's particularly fine at 100μm then a helium atom is ~3 millionth of the size and a caesium atom is ~0.5 millionth of the size. So if a helium atom was as large as a grain of salt a grain of salt would be ~100m wide and for a caesium atom it would be ~16m wide.

    I'm pretty sure my math is correct there :wink:
     
  5. Feb 20, 2012 #4
  6. Feb 20, 2012 #5
    If I remember correctly, an atom is roughly in the 10^-11 - 10^-10 scale, and an average grain of salt could have a diameter of, let's say, 10^-3 m (assuming it's a sphere).

    This leaves you with a diameter ratio of about 50 million.
     
  7. Feb 20, 2012 #6
    So what object would represent the size of the grain of salt?
     
  8. Feb 20, 2012 #7

    Ryan_m_b

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    See my post #3 above.
     
  9. Feb 20, 2012 #8
    I did but you didnt mention any objects.
     
  10. Feb 20, 2012 #9

    Ryan_m_b

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    16 metres long is roughly five cars. 100 metres long is roughly the width of the international space station. That's obviously just length so use your imagination to make it 3d.
     
  11. Feb 20, 2012 #10

    Mark44

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    A hydrogen would be a bit smaller, being a single proton.
     
  12. Feb 21, 2012 #11
    Thanks Ryan. I wasnt sure if you meant miles or meters.

    Is it possible to estimate which atomic scale that transistor was manufactured at from the link I posted? And what size would a grain of salt represent from my original question compared to the size of that transistor?

    Thank you for any help!!
     
  13. Feb 23, 2012 #12
  14. Feb 23, 2012 #13

    Ryan_m_b

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    Well the atom they mention is phosphorous which is roughly 180pm in size (note that atom "size" can vary based on how they bond IIRC).

    Taking a grain of salt to be 100μm in size: 100000000pm/180pm = 555555.55
    100μm*555555.55 = 55555555μm = 55555.555mm = 55.555555m

    So a grain of salt would be ~half the size of a 100m sprint track.
     
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