How many Rb atoms to fit on a 9Cm^2 square?

  • Thread starter UnD3R0aTh
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  • #1
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1. The problem is in the attachments



2. Basic chemistry knowledge



3. The radius of one Rb atom is 4.95/2 time 10^-8 cm, we calculate the area then divide 9 into the area of one atom, we get the number of atoms, why is 4.7 x 10^15 atoms wrong?
 

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Answers and Replies

  • #2
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There are empty spaces between the atoms - they need more space than just pi*r2.
 
  • #3
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exactly my thought, how to calculate that?!
 
  • #4
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Does this sketch help?
 

Attachments

  • atoms.png
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  • #5
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excellent, i solved the first one, but the second one i'm not really sure how to calculate the side of the triangle that's enclosing one atom!!!!
 
  • #6
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You can draw an equilateral triangle in the lattice.
 
  • #7
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yes but it looks like it's side is longer than the diameter, how to calculate it's length?!
 
  • #8
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no wait, the triangles do not work, they overlap! parallelograms work! how to calculate the area of a parallelogram using it's sides?
 
  • #9
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Then you are drawing the wrong triangles. Use the centers of the atoms, this is easier. Afterwards, find out how many atoms per triangle (or triangles per atom) you have.
 
  • #10
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can u plz draw a diagram like u did with the first one?
 
  • #12
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i don't know to how to draw this, using what program?
 
  • #13
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Every drawing program can draw lines. Windows always comes with Paint, for example.
 
  • #14
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pffffft i've been thinking about this problem for far too long i'm at my wits end, i really need to stop wasting my time with this and study, i feel nervous already cause i wasted so much time, plz give me a more strong hint, save me some time, thank you
 
  • #15
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solved it
 

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