Resources written by Chas McCaw for sixth form chemistry teaching and beyond.
General interest:
Graphite Buckminsterfullerene Ice White phosphorus Benzene Cyclohexane AdamantaneCubic:
Sodium Caesium chloride Polonium Copper Halite Fluorite Antifluorite Zinc blende DiamondNon-cubic:
Hexagonal:
Magnesium WurtziteTetragonal:
RutileTrigonal:
α-quartzTriclinic:
Copper(II) sulfateOrthorhombic:
α-SulfurMonoclinic:
β-SulfurOther elements that adopt this structure: Li, K, Rb, Cs, Ba, Ra, V, Cr, Fe, Nb, Mo, Ta, W and Eu.
A unit cell of sodium is shown to the left. The black wireframe just marks out the repeating unit of space in the structure - the lines are not supposed to depict any kind of chemical bond. All the corner positions and the body centre are occupied with sodium atoms. Note how the unit cell corners are in the centres of the relevant sodium atoms. This means that only one eighth of the corner atom is actually inside a given unit cell. Therefore the total atom occupancy inside a unit cell is equal to (8 x 1/8) + 1 = 2. This can be appreciated fully by looking at the structure on the next page.
Go to page 5 to look at how the unit cells stack together to yield the bulk structure of sodium.