Learning outcomes - after studying this topic, you should be able to:

• define and give examples of alloys
• show how close packing of spheres can lead to hexagonal or cubic close packing
• identify the major metal structures - cubic close packed, hexagonal close packed, body centred cubic and simple cubic
• list the coordination number, packing efficiency and number of atoms in the unit cell of each of these packing types
• identify unit cells for cubic packing
• relate the unit cell contents and the stoichiometry
• calculate the packing efficiency in cubic unit cells
• rationalize the structure of simple ionic solids in terms of filling of the holes in the close packed structures

• Section 7.2 (in Blackman, Bottle, Schmid, Mocerino and Wille, Chemistry, 3^rd Edition, 2015 (John Wiley))