solids

solids

1. crystalline

   • comprising a well ordered array of atoms or molecules
   • based on units that compose the solid
     • molecular solids
       • ex: ice, dry ice (CO2)
       • held together by inter forces
         • LD, d-d, H
       • low mp
         • ^ inter forces - ^ mp
     • ionic solids
       • ex: table salt (NaCl), CaF2
       • held together by coulombic interactions
       • coordination #
         • # surrounding particles
           • reps # close cat-an interactions
             • lower PE
       • arrangements
         • primitive: 1/8*8
         • bcc: 1/8*8 + 1
         • fcc: 1/8*8 + 1/2*6
     • atomic solids
       • based on the type of interactions btwn atoms
         • nonbonding
           • held together by weak dispersion forces
           • low mp
             • ^ molar mass - ^ mp
           • ex: solid noble gases
           • closet packet structures
         • metallic
           • ex: Fe, Au
           • held together by metallic bonds
             • interaction of metal cations w/ the sea of e- that surround them
           • closet packet structure
           • varying mp
         • network covalent
           • ex: diamond, graphite, SiO2
           • not clos pack
           • held by cov bonds
             • e- confined to cov bonds, not free to flow >doesn't conduct electricity
       • ex: Xe, Fe, SiO2
   • model for bonding
     • e- sea model
     • band theory model
       • applies to met, cov s
       • we combine the atomic orbitals of the atoms w/i a solid crystal to form orbitals
         • that aren't localized on individual atoms
           • but delocalized over the entire crystal

2. amorphous

   • having no long range order