233k views
0 votes
The different unit cell types have a different packing efficiency. The simple cubic has the least efficient packing and the face-centered cubic has the most efficient packing (sometimes the face-centered cubic is called cubic closest packing). You can determine what percent of the unit cell is occupied by (1) determining the volume of the whole unit cell and (2) determining the volume of the occupied space by the atoms in the unit cell. Remember that the volume of a cube is V

1 Answer

1 vote

Answer:

The answer is "52.8".

Step-by-step explanation:

Please find the graph file in the attachment.

They have the atoms in 8 corners with one unit cell in an one so mesh (SCC).

Atoms throughout the corner contribute
(1)/(8)to both the cell unit

Atom number per SCC unit cell,
Z = (8 * (1)/(8)) = 1

Let 'r' become the atom's radius.
r = 3.43* 10^(-8)\ \ cm

We can see from the diagram that edge length
AB = a = 2r


Packing\ efficiency = ((1 \ atom \ Volume * Z))/(Volume \ of \ unit\ cell * 100)\\\\


= ((4)/(3)* \pi * r^3 * 1)/(a^3 * 100)\\\\=((4)/(3)* \pi * r^3 * 1)/((2r)^3 * 100) \\\\=((4)/(3)* \pi *( 3.43* 10^(-8)cm)^3 * 1)/((2* 3.43* 10^(-8)cm)^3 * 100)\\\\= 52.8 \%

The different unit cell types have a different packing efficiency. The simple cubic-example-1
User KKO
by
3.7k points