Chapter 3 - 1ISSUES TO ADDRESS...What is the difference in atomic arrangement between crystalline and noncrystalline solids? What features of a materials atomic structure determine its density?Under what circumstances does a material property vary with the measurement direction?Crystalline structures of metals and alloysecture 3! "he #tructure of Crystalline #olidsChapter 3 - $%on dense& random pac'ing(ense& ordered pac'ing(ense& ordered pac'ed structures tend to havelower energies)*nergy and +ac'ingEnergyr"ypical neighbor bond lengthtypical neighbor bond energyEnergyrtypical neighbor bond lengthtypical neighbor bond energyChapter 3 - 3atoms pac' periodic& 3( arraysCrystalline materials)))-metals-many ceramics-some polymersatoms have no periodic pac'ing%oncrystalline materials)))-comple, structures-rapid coolingcrystalline #i-$noncrystalline #i-$./morphous. 0 %oncrystalline/dapted from 1ig) 3)$23b4& Callister & Rethwisch 9e. /dapted from 1ig) 3)$23a4& Callister & Rethwisch 9e. 5aterials and +ac'ingSi Oxygentypical of!occurs for!Chapter 3 -The Cubic SystemOne AtomTwo AtomsFour Atomsb=4rb2=2a2S=a2V=a3Lattice Parameter (a) and Atomic Radius (r)FCCChapter 3 -Chapter 3 - 6 5etallic Crystal #tructures 7ow can we stac' metal atoms to minimi8e empty space?$-dimensionsvs.%ow stac' these $-( layers to ma'e 3-( structuresChapter 3 - 9"end to be densely pac'ed):easons for dense pac'ing!- "ypically& only one element is present& so all atomic;;;;;; are the same)- 5etallic bonding is not directional) - %earest neighbor distances tend to be small inorder to lower bond energy)- *lectron cloud shields cores from each other)5etals have the simplest crystal structures)We will e,amine three such structures)))5etallic Crystal #tructuresChapter 3 -