Cadmium iodide, lattice energy

The halides of cadmium demonstrate the effect on structure of the easier polarisation of an anion by a smaller cation. Cdp2 has the cubic fluorite lattice but the chloride, bromide and iodide form hexagonal crystals based on layer lattices (p. 150). The distances between the layers increase from the chloride to the iodide, with a corresponding reduction in lattice energies. 

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