Interatomic spacing concept confusion

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Discussion Overview

The discussion revolves around the concept of interatomic spacing, particularly in the context of atomic models and representations. Participants explore the differences in visual representations of atoms and their implications for understanding atomic interactions and packing in materials.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about the differences in images depicting atomic structures, questioning why atoms appear to be spaced apart in some representations.
  • Another participant asks for clarification on how the images imply different atomic arrangements.
  • A participant explains that atoms are not rigid spheres and that their interactions are governed by the charge from the electron shell, which diminishes with distance.
  • It is noted that the representation of atoms in diagrams is arbitrary and can vary for clarity.
  • A participant raises a concern about calculating density in unit cells, suggesting that this might imply atoms are packed together as spheres, questioning the implications of atomic radius.
  • Another participant clarifies that atomic radius is derived from the distance between neighboring atoms and emphasizes that atoms do not have a defined surface, thus they do not "touch" like solid spheres.
  • It is mentioned that atoms repel when too close and attract when separated, which helps maintain spacing in a crystal lattice.

Areas of Agreement / Disagreement

Participants express differing views on how to interpret atomic spacing and the implications of atomic models. There is no consensus on the best way to visualize or understand interatomic spacing.

Contextual Notes

Participants acknowledge the limitations of atomic models and the arbitrary nature of their representations. The discussion highlights the complexity of atomic interactions and the challenges in reconciling visual representations with physical properties.

Who May Find This Useful

This discussion may be of interest to students and educators in physics and chemistry, particularly those exploring atomic theory, material science, and the nature of atomic interactions.

engineering810
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I am trying to understand the concept of interatomic spacing. Below is a link to three pictures, and my questions is: why are they different? I thought atoms were packed together touching each other like in the first picture but the second and third imply otherwise. Any explanation or help is appreciated as I have been trying to find the answer for hours on end now. Thank you for any help in advance!

http://s1300.photobucket.com/user/waveriderr810/library/
 
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engineering810 said:
but the second and third imply otherwise
How so?
 
Bystander said:
How so?

In the second and third pictures the atoms appear to be spaced out and have space in between them, which represents their interatomic distance. Aren't atoms all packed together therefore there would be no spacing between them?
 
Atoms are not hard billiard balls. They interact via the charge from the electron shell. This charge drops off with distance.
When diagramming an atom, it is arbitrary how large you make the sphere, since it has no real-world counterpart.
How one represents atoms in a diagram is a matter of taste and of clarity.
 
DaveC426913 said:
Atoms are not hard billiard balls. They interact via the charge from the electron shell. This charge drops off with distance.
When diagramming an atom, it is arbitrary how large you make the sphere, since it has no real-world counterpart.
How one represents atoms in a diagram is a matter of taste and of clarity.

Thank you for responding, this actually makes sense to me but my teacher has us calculating the density in unit cells depending on how much space the atom is occupying and how much space is vacant. Wouldn't this imply they are spheres packed together also touching each other? Maybe the atomic radius implys something else I'm not understanding?
 
Atomic radius is calculated by diving the distance between centers of neighboring atoms into two. As Dave wrote atoms don't have a well defined surface, so they don't "touch" each other like balls do. However, atoms do interact - if you squeeze them too closely they will repel each other, if you separate them, they will have tendency to attract each other. These forces keep atoms spaced in the crystal lattice despite the fact they don't "touch".
 

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