Closed Packing: Definition & Planes

[gracy]

what is definition of closed packing?a close packing plane is a plane that the atoms cannot be packed any closer?

 

[DrClaude]

what is definition of closed packing?a close packing plane is a plane that the atoms cannot be packed any closer?

That's "close packing,", not "closed." Yes, it means that atoms, taken as spheres, cannot be closer to one-another. See http://departments.kings.edu/chemlab/animation/clospack.html

 

[gracy]

it means that atoms, taken as spheres, cannot be closer to one-another.

atoms have to be sphere? in definition word sphere is present?

 

[DrClaude]

The term "close packing" comes from the part of geometry that deals with the packing of spheres, i.e., how to arrange spheres in 3D. There are two packing of spheres which the density of the spheres, cubic close packing and hexagonal close packing. If you take the center of the spheres in these packing configurations to be the position of an atom, you will find crystal structures that have the same arrangement as these close-packed sphere. Therefore, by taking the atom as a sphere, you can imagine that the crystal structure results from the atoms being as close as possible to each other. Of course, atoms are not spheres and don't have fixed sizes, so can always put them closer together (e.g., by compression).

I found a better link than my previous suggestion:
http://chemwiki.ucdavis.edu/Wikitex...es_of_Matter/Cubic_Lattices_and_Close_Packing

 

[gracy]

, i.e., how to arrange spheres in 3D

what about 2D?is close packing not applied in 2D?

 

[DrClaude]

what about 2D?is close packing not applied in 2D?

Yes, you can apply it to 2D. It is just that crystal lattices are usually 3D. I'm sorry if I led you astray by discussing spheres in 3D. But the links I gave also discuss the 2D case.

 

[gracy]

Yes, you can apply it to 2D. It is just that crystal lattices are usually 3D. I'm sorry if I led you astray by discussing spheres in 3D. But the links I gave also discuss the 2D case.

Thanks a lot.May God bless you.