What are the common atomic radii used for chemical pictures?

In summary, the common atomic radii used for drawing chemical pictures vary and there are no set rules. Most programs use half the covalent radii for their default ball-and-stick mode. Spacefill models would be around the full covalent radius. However, these radii do not have much physical meaning and are primarily used for visual representation of structures. For more detailed information about orbitals, bonding, and electron densities, other methods should be used.
  • #1
somasimple
Gold Member
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Hi all,

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

Is it the ionic or calculated or?

Thanks.
 
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  • #2
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.
 
  • #3
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.
 

1. What is atomic radius?

Atomic radius is the distance from the center of an atom's nucleus to the outermost electron shell. It is usually measured in picometers (pm) or angstroms (Å).

2. How is atomic radius measured?

Atomic radius is typically measured using X-ray diffraction or spectroscopic techniques. These methods involve analyzing the diffraction patterns or energy levels of atoms to determine their size.

3. What factors affect atomic radius?

The main factor that affects atomic radius is the number of electrons an atom has. As the number of electrons increases, the outermost electron shell becomes more distant from the nucleus, resulting in a larger atomic radius.

4. How does atomic radius change across the periodic table?

Atomic radius generally decreases from left to right across a period in the periodic table. This is due to the increasing number of protons in the nucleus, which causes a stronger attraction for the electrons and results in a smaller atomic radius.

5. Can atomic radius be visualized with pictures?

Yes, atomic radius can be visualized with pictures. There are many diagrams and models that represent the relative sizes of different atoms. However, it is important to keep in mind that these pictures are not to scale and are only meant to provide a visual representation of atomic size.

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