Section 12.1-12.2
1. Define metallic solids
2. Define ionic solids
3. Define covalent-network solids
4. Define molecular solids
5. Define polymers
6. Define nanomaterials
7. Define crystalline solids
8. Define amorphous solids
9. Define crystal lattice
10. Define lattice points
11. Define lattice vectors
12. How many points is a two-dimensional lattice defined?
13. Draw figure 12.3 and explain what is seen in the drawing.
14. Define oblique lattice
15. Define square lattice
16. Define rectangular lattice
17. Define hexagonal lattice
18. Define rhombic lattice (or centered rectangular lattice)
19. Draw the 5 two-dimensional lattices from figure 12.4
20. How many points is a three-dimensional lattice defined? What is name of the object that is made from the
lattice vectors?
21. Define and draw the primitive lattices.
22. Define body centered cubic lattice
23. Define face-centered cubic lattice
24. Define motif
25. Draw the motif for graphene
26. What can X-ray diffraction show about crystalline structures?
27. Covalent bonding occurs in both molecular and covalent-network solids. Which of the following statements
best explains why these two kinds of solids differ so greatly in their hardness and melting points? (a) The
molecules in molecular solids have stronger covalent bonding than covalent-network solids do. (b) The
molecules in molecular solids are held together by weak intermolecular interactions. (c) The atoms in
covalent-network solids are more polarizable than those in molecular solids. (d) Molecular solids are denser
than covalent-network solids.
28. What kinds of attractive forces exist between particles (atoms, molecules, or ions) in (a) molecular crystals,
(b) covalentnetwork crystals, (c) ionic crystals, (d) and metallic crystals?
29. Indicate the type of solid (molecular, metallic, ionic, or covalent- network) for each compound: (a) CaCO3,
(b) Pt,(c) ZrO2 (melting point, 2677 °C), (d) table sugar (C12H22O11), (e) benzene (C6H6), (f) I2.
30. A white substance melts with some decomposition at 730 °C. As a solid, it does not conduct electricity, but
it dissolves in water to form a conducting solution. Which type of solid molecular, metallic, covalentnetwork, or ionic) might the substance be?
31. (a) Draw a picture that represents a crystalline solid at the atomic level. (b) Now draw a picture that
represents an amorphous solid at the atomic level.
32. Two patterns of packing for two different spheres are shown here. For each structure (a) draw the twodimensional unit cell; (b) determine the angle between the lattice vectors, g, and determine whether the
lattice vectors are of the same length or of different lengths; and (c) determine the type of two-dimensional
lattice (from Figure 12.4).
33. Imagine the primitive cubic lattice. Now imagine grabbing the top of it and stretching it straight up. All
angles remain 90°. What kind of primitive lattice have you made?
34. Which of the three-dimensional primitive lattices has a unit cell where none of the internal angles is 90°? (a)
Orthorhombic, (b) hexagonal, (c) rhombohedral, (d) triclinic, (e) both rhombohedral and triclinic.
35. What is the minimum number of atoms that could be contained in the unit cell of an element with a bodycentered cubic lattice? (a) 1, (b) 2, (c) 3, (d) 4, (e) 5. The unit cell of nickel arsenide is shown here. (a)
What type of lattice does this crystal possess? (b) What is the empirical formula?