The Crystalline Solid State. Chapter 7. Crystalline Solid State. Many more “molecules” in the solid state. We will focus on crystalline solids composed of atoms or ions. Unit cell – structural component that, when repeated in all directions, results in a macroscopic (observable) crystal.
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Let’s look at a few (NaCl, CaF2, and CaCl2).
M+(g) + X-(g) MX(s)
G = H - TS (standard state), 2nd term can be ignored
MX(s) M+(g) + X-(g) HL (standard molar enthalpy change)
Currently, we are interested in lattice formation.
zA, zB = ionic charges in electron units
r0 = distance between ion centers
e = electronic charge
4o = permittivity of a vacuum
e2/ 4o = 2.307 10-28 J m
Calculation would be performed on each cation/anion pair (nearest neighbor).
NA = Avogadro’s constant
A = Madelung’s constant, value specific to a crystal type (in table). This is a sum of all the geometric factors carried out until the interaction become infinitesimal.
C’ = constant (will cancel out when finding the minimum)
NaCl and CaBr2
This would be called an ‘s band’. A similar model can be constructed for the p-orbitals and d-orbitals.
For a TiO6 monomer (no significant -bonding).
An approximation of the ‘bands in the solid structure.
Cheetham and Day
Individual units, chains, multiple chains (ribbons), rings, sheets and 3-d networks.
(illustrate with softwares)
Asbestos mineral (fibrous)