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-SulfurSince the geometry around the titanium ions is octahedral, the structure can be represented as a three-dimensional array of octahedra. The structure on the left shows the octahedra of oxide ions around each titanium ion. The octahedra are coloured silver as they have titanium at the centre. In this structure the octahedra that appear to be pointing up and to the left only seem to be sharing corners whereas the other octahedra are sharing edges too. Earlier arguments suggested that the octahedra are equivalent, which would require the same geometric relationships with neighbouring octahedra. They can be seen to be truly equivalent by looking at a larger sample of bulk.
Go to page 9 to consider the polyhedral representation in a larger sample of bulk.