Exploring Hexagonal, Face-Centered & Body-Centered Packings

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Hexagonal closest packing (HCP) and face-centered cubic (FCC) packing are both highly efficient arrangements, achieving the same packing efficiency, while body-centered cubic (BCC) packing is less efficient due to its less compact arrangement. The coordination number, which indicates how many atoms surround a central atom, directly relates to packing efficiency and density, as it reflects the mass of atoms in a given volume. HCP and FCC both have a coordination number of 12, maximizing density, whereas BCC has a coordination number of 8, resulting in lower density. The relationship between coordination number, packing, and density can be understood as density being mass per unit volume, where higher coordination numbers typically lead to higher density. Understanding these concepts is crucial for analyzing the efficiency of different atomic arrangements.
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Looking at hexagonal closest packing, face centred (or closest packing) and body-centered packing.

So I need to know abit about each.

I would think body-centered was the least efficient having looked at the arrangment. The main layer has to be centered a certain way to fit the rest..which means that he spheres are not close to each other but it looks more organized. Hexagonal looks the most packed to me.

I also need to know..in terms of volume how do thetwo more efficient ways of packing compare..and also what is the relationship between coordination number, packing and density (as mass/volume)?

Thanks
 
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anybody have any idea?
 
all of this should be explained explicitly in you text.
 
all of this should be explained explicitly in your text.

ignore the previous post, it seems that the deletion function is not working.
 
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Your text must also teach you how to derive the packing efficency/fraction. Once, you learn how this works, it's fairly simple to show that the FCC and HCP are both equally dense. Without actually doing the math, it's hard to compare pqacking efficiency.
 
Ok, I figured that part out.

I still don't see the relationship between coordination number, packing and density. (as mass/volume)

This is what I wrote: (makes sense to me, but I could be way off)


We can look at coordination number as mass, because it is the number of atoms
that are packed around the space lattices. While the packing refers to the volume since the type of packing is the way the spheres are structured. If they are placed a certain way they will occupy a bigger or lower volume. The density
is the relationship between those two (the mass per volume).
 
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