Presentation on theme: "Crystals and Their Structure. Unit Cells in the Cubic Crystal System."— Presentation transcript:
Crystals and Their Structure
Unit Cells in the Cubic Crystal System
Body - Centered Cubic
Face - Centered Cubic
Cubic Closest Packing of Frozen Argon
Cubic Closest Packing of Frozen Methane
Counting Cell Occupancy
Volume of the Unit Cell r is the radius of an atom in the unit cell r The volume of the unit cell is L 3 L But how do you get L? The Pythagorean Theorem, of course!
Volume of the Unit Cell L L r r r r
Calculating Packing Efficiency L L Packing efficiency is the ratio of the space occupied in the unit cell to the volume of the unit cell Cell occupancy = 4 r r r r
Crystalline and Amorphous Silicon Dioxide Cristobalite, one of the crystalline forms of silicon dioxide, shows cubic closest packing. A glass made from silicon dioxide shows the amorphous disoriented structure.