1. Solids
Image:Wikimedia Commons User Alchemistry-hp

2. Types of Solids
Crystalline Solids: highly regular arrangement of their components
Amorphous solids: considerable disorder in their structures (glass, plastic).

3. Representation of Components in a Crystalline Solid
Lattice: A 3-dimensional system of points designating the centers of components (atoms, ions, or molecules) that make up the substance.

4. Bragg’s Law
xy + yz = n and xy + yz = 2d sin
 n = 2d sin 

5. Crystal Structures - Cubic
Simple
Face-Centered
Body-Centered
**Knowledge of specific types of crystal structures and the study of the specific varieties of crystal lattices for ionic compounds is beyond the scope of this course and the AP Exam.

6. Crystal Structures - Monoclinic
Simple
End Face-Centered

7. Crystal Structures - Tetragonal
Simple
Body-Centered

8. Crystal Structures - Orthorhombic
Simple
End
Face-Centered
Body
Centered
Face
Centered

9. Crystal Structures – Other Shapes
Rhombohedral
Hexagonal
Triclinic

10. Closest Packing: Single Layer
Photographer : Thierry Dugnolle

11. Closest Packing: Multiple Layers
Model: Packing uniform, hard spheres to best use available space. This is called closest packing. Each atom has 12 nearest neighbors.

12. Metal Alloys
Substitutional Alloy: some metal atoms replaced by others of similar size.
brass = Cu/Zn

13. Metal Alloys (continued)
Interstitial Alloy: Interstices (holes) in closest packed metal structure are occupied by small atoms.
steel = iron + carbon

14. Network Atomic Solids
Some covalently bonded substances DO NOT form discrete molecules.
Diamond, a network of covalently bonded carbon atoms
Graphite, a network of covalently bonded carbon atoms

15. Graphene
Graphene can be described as a one-atom thick layer of graphite.
High-quality graphene is strong, light, nearly transparent and an excellent conductor of heat and electricity. 
Andre Geim and Konstantin Novoselov at the University of Manchester won the Nobel Prize in Physics in 2010 "for groundbreaking experiments regarding the two-dimensional material graphene"
Source: Wikipedia

16. Semiconductors
Pure silicon is structurally the same as diamond, but is a semiconductor rather than an insulator.
The conductivity increases at higher temperature.
Conductivity of silicon can be improved by doping with other elements.

17. n-type Semiconductors
Substances whose conductivity is increased by doping with atoms having more valence electrons than the host crystal. Here, silicon (4 valence e-’s) is doped with phosphorus (5 valence e-’s).

18. p-type Semiconductors
Substances whose conductivity is increased by doping with atoms having fewer valence electrons than the host crystal. Here, silicon (4 valence e-’s) is doped with aluminum (3 valence e-’s).

19. Molecular Solids Strong covalent forces within molecules
Weak covalent forces between molecules
Sulfur, S8
Phosphorus, P4

20. Ionic Solids
Ionic compounds at room conditions are generally crystal lattices of alternating cations and anions.
NaCl Unit Cell
Sodium chloride and sodium fluoride form simple cubic crystals.
Sodium Fluoride

21. Ionic Solids
Ionic compounds are represented by empirical formulas, because they do not form discrete molecular structures.
Lithium niobate, LiNbO3