Crystals have regular repeating structures called unit cells.
Click on the tabs below to explore 3 common types of unit cells.
"Actual Size Atoms" shows the accurately-sized atoms but can be hard to visualize.
The unit cell may be easier to visualize with "Smaller Atoms".
Rotate the unit cell using left mouse click and drag. Move the unit cell using right mouse click and drag.
1. Pause each unit cell in the same position and take a screenshot (suggestioned position = looking directly at a front face).
2. Compare the sizes of the different types of unit cells.
3. Calculate how many atoms are inside each unit cell (note: only consider the parts INSIDE the unit cell).
4. Calculate the x, y, z coordinates of each atom in each unit cell, assuming the center point is <0,0,0>. To do this, you will need the following radius values:
BCC (Cr) r = 125 um
FCC (Al) r = 143 um
HCP (Zn) r = 133 um
1. The purple bits in HCP are overlapping from neighboring cells.