1 / 12

Solids

Solids. crystalline. quartz. well defined structures. amorphous. glass. no orderly structure. SiO 2. crystal lattice. system of points. describes arrangement of particles. unit cell. repeating structural unit. lattice. 7 unit cells. simple cubic. formed from packing spheres.

dewei
Download Presentation

Solids

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Solids crystalline quartz well defined structures amorphous glass no orderly structure SiO2 crystal lattice system of points describes arrangement of particles

  2. unit cell repeating structural unit lattice 7 unit cells simple cubic formed from packing spheres

  3. crystalline solids unit cells hexagonal closest packing cubic packing in 3 dimensions hexagonal closest pack cubic closest pack simple cubic body centered cubic “abab” layers “abca” layers “abab” layers “aaa” layers

  4. Three-Dimensional Cubic Lattices Simple cubic a a a 1/8 x 8 = 1 particle coordination number = 6 Body-centered cubic a b a b (1/8 ) x 8 + 1 = 2 particles coordination number = 8 Face-centered cubic cubic closest pack a b c a b c (1/8 ) x 8 + (1/2 ) x 6 = 4 particles coordination number = 12

  5. Calculation of atomic radii Cu faced-centered cubic density = 8.92 g/cm3 r+2r+r mass = 63.546 g/mol 63.546 g 4 atoms 1 mol cm3 unit cell 6.022 x 1023 atoms mol 8.92 g 1/3 = 3.617 x 10-8 cm ( ) 4.732 x 10-23 cm3 / unit cell lattice parameter, a = (4r)2 (3.617 x 10-8)2 + (3.617 x 10-8)2 1 x 10-2 m 1 pm r = 1.279 x 10-8 cm = 127 pm 1 x 10-12 m 1 cm

  6. d X-Ray Diffraction by Crystals diffraction interference between waves caused by object in their path constructive or destructive Bragg Equation n = 2d sin 

  7. Types of Crystalline Solids Covalent Ionic Molecular molecules in lattice atoms in lattice ions in lattice m.p. depends on bonding forces ionic covalent H-bonding H2O 0oC Cdiamond 3550oC NaCl 800OC

  8. Covalent solids atoms in lattice carbon sp3 sp2 sp2 diamond graphite buckminsterfullerene hardest material known conduct electricity -  e- doesn’t conduct electricity

  9. Covalent solids atoms in lattice atom of 1 metal metals every lattice point - body-centered cubic face-centered cubic melting point hexagonal close packed Na 97oC share valence e- e- “sea” Cr 1890oC good conductors substitutional alloy brass steel interstitial alloy

  10. Ionic Solids composed of charged species – unit cell neutral stoichiometry of compound each unit cell - anions and cations different in size anions at lattice points cations in “holes” NaCl face-centered cubic CsCl simple cubic r = 0.225 R r = 0.414 R too small trigonal hole tetrahedral hole octahedral hole

  11. Molecular Solids molecules in lattice hemoglobin reaction center 1962 1988 Perutz and Kendrew Deisenhofer, Huber and Michel

More Related