Educator

Types of Solids, X-Ray Diffraction, Unit Cells

• Crystalline solids ordered: test is X-ray diffraction; fracture along planes

• Amorphous solids; not ordered; fracture along curves e.g. glass

• Types of crystalline solid include metals; ionic crystals like NaCl; molecular crystals like sucrose; network solids like diamond, quartz

• Bragg’s Law gives structures from X-ray diffraction

• Unit cell represents symmetry of whole crystal by abstracting a small portion

• Simple cubic, face-centered cubic, and body-centered cubic unit cells; learn how to draw each

• Unit cell contents and densities of materials; master connections between atomic radii, unit cell dimensions, and density

• First Law of Thermo and formation of ionic crystals from elements, e.g. NaCl

• Lattice energy and relationship to constitution of ionic crystals