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-SulfurIn the structure to the left a blue wireframe is drawn around the six oxide ions neighbouring the central titanium ion. This illustrates the octahedral hole in which the titanium ion resides. However, it is not a perfectly regular octahedron: it is tetragonally distorted, with two of the bonds (opposite each other) longer than the other four. A yellow wireframe is drawn around an oxide ion to show the geometric relationship of the three titanium ions surrounding it. These titanium ions form a triangle around the oxide, but an isosceles rather than an equilateral triangle.
The following pages take a more advanced approach.
Go to page 6 to consider the equivalence of the octahedral sites.