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Atomic radii for pictures.

  1. Sep 18, 2010 #1


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    Gold Member

    Hi all,

    What are the common atomic radii that are used for drawing chemical pictures?

    Is it the ionic or calculated or?

  2. jcsd
  3. Sep 18, 2010 #2


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    Staff: Mentor

    Whatever, as far as I am aware there are no set rules. There is some obvious logic that you can apply, but as long as your pictures are not drawn to be a scientific tool (like DNA models built by Watson and Crick) you don't have to pay too much attention to it. Just be consistent.
  4. Sep 18, 2010 #3


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    Science Advisor

    My program uses (for its default ball-and-stick mode) half the covalent radii. (vdW radii look a bit too chunky). Most programs use something similar. (To the extent I sometimes see papers with images that might have been made with my program, but I can't be sure) "Spacefill" models would be around the full covalent radius, or slightly larger.

    It's not like the spheres in these pictures have much in the way of physical meaning; you're only drawing the structure.
    If you want to say something about orbitals or bonding or electron densities, then that's what you plot, not ball-and-stick models.
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