Q 1(a) [50 Marks] Discuss the principles of atomic packing in three dimensions with reference to crystalline elemental metallic solids and compare this to the types of close packing observed in binary alkaline earth metal salts. Rationalise why the crystal structures of binary salts M.Xm deviate from the ideal close packing model and explain, with reasoning and diagrams, the principal differences between the crystal structures of rutile (TiO2) and anti-rutile