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Chapter 13 The Chemistry of Solids

Chapter 13 The Chemistry of Solids. Types of Solids Metals Network Ionic Molecular Amorphous. Chapter 13 The Chemistry of Solids. Types of Solids Examples Metals Copper Network Quartz Ionic NaCl Molecular CO 2 , CI 4 Amorphous glass, polyethylene.

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Chapter 13 The Chemistry of Solids

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  1. Chapter 13 The Chemistry of Solids • Types of Solids • Metals • Network • Ionic • Molecular • Amorphous

  2. Chapter 13 The Chemistry of Solids • Types of SolidsExamples • MetalsCopper • NetworkQuartz • IonicNaCl • MolecularCO2, CI4 • Amorphousglass, polyethylene

  3. Types of SolidsCharacteristics • MetalsCopper - malleable • NetworkQuartz – non-malleable • Molecularsulfur (S8) • CO2, CI4 – low melting pt • Ionic &muscovite– cleaves easy • Network, • Layered structure

  4. The Chemistry of Solids What characteristic do these solids share?

  5. The Chemistry of Solids What characteristic do these solids share? Repeating Structural Pattern other terms: Lattice Array Crystal Structure or Crystal Lattice

  6. The Chemistry of Solids UNIT CELL is the smallest piece of the pattern that generates the lattice. UNIT CELL is a conventional choice. May have several unit cells possible, Different in shape and/or size. Translation directions

  7. The Chemistry of Solids UNIT CELL is a conventional choice. May have several unit cells possible, Different in shape and/or size.

  8. Three Types of Cubic Unit Cells c b a Body Centered Cubic Face Centered Cubic Simple Cubic

  9. These Three Cubic Unit Cells are Structures of most Metallic Elements (also hexagonal, hcp, to be seen Friday) Cu, Ag, Au are all fcc Cr, Mo, W are all bcc Only Po is simple cubic (rare— why?) Body Centered Cubic Face Centered Cubic Simple Cubic

  10. One result of a metal’s “choice” to adopt a cubic, bcc or fcc lattice are metal properties Simple Cubic Body Centered Cubic Face Centered Cubic

  11. Packing a Square Lattice: Makes a simple cubic cell

  12. Can you pack spheres more densely? The Rhomb is the Unit CellShape of Hexagonal Lattices

  13. Closest Packing: hexagonal layers build up 3D solid

  14. Find the triangular gaps in the Pink layer

  15. Note how layers “sit” on top of each other: The Cyan layer covers the “up” triangles of the Pink layer The Yellow layer covers the “down” triangles of the Pink layer

  16. This packing sequence is ABCA BC, Where B and C cover different “holes” in A A B C A B C

  17. Packing direction A B C A B C ccp Cubic Closest Packing: A B C A B C … A C B A C B A Packing direction

  18. CCP viewed as packing layers CCP viewed unit cell; LOOK! It’s face centered cubic!!! CCP = FCC!! ….mmmMMM C B A C B A

  19. Smaller atom like C in iron Larger atom like P in iron Effect of added atoms and grains on metal structure. Defects and grain boundaries “pin” structure. All these inhibit sliding planes and harden the metal. Second crystal phases precipitated

  20. Defects in metal structure

  21. From Metals to Ionic Solids Will ionic solids pack exactly like metallic solids?

  22. From Metals to Ionic Solids • Build up Ionic Solids conceptually like this: • assume Anions are larger than Cations, r- > r+ • pack the Anions into a cubic lattice: ccp, simple or bcc • add Cations to the interstitial spaces (“Mind the gap!”) r- + r+ 2 xr- 2 xr-

  23. How to draw this The Simplest Ionic Solid is CsCl, simple cubic Start with simple cubic Unit cell of Cl- ions Then add one Cs+ in center Z = C. N. (Cs) =

  24. How to make NaCl: start with fcc unit cell of Cl- ions

  25. Add Na+ in between

  26. Add Na+ in between, everywhere

  27. Z = C. N. (Na) =

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