5 Steps to a 5 AP Chemistry

cation is surrounded by six chloride anions, and each chloride anion is surrounded by

six sodium cations.

4. In metallic solids,metal atoms occupying the crystal lattice are held together by metal-
   lic bonding. In metallic bonding,the electrons of the atoms are delocalized and are
   free to move throughout the entire solid. This explains electrical and thermal conduc-
   tivity, as well as many other properties of metals.


5. In covalent network solids,covalent bonds join atoms together in the crystal lattice,
   which is quite large. Graphite, diamond, and silicon dioxide (SiO 2 ) are examples of net-
   work solids. The crystal is one giant molecule.

Phase Diagrams

The equilibrium that exists between a liquid and its vapor is just one of several that can exist

between states of matter. A phase diagramis a graph representing the relationship of a sub-

stance’s states of matter to temperature and pressure. The diagram allows us to predict

which state of matter a substance will assume at a certain combination of temperature and

pressure. Figure 12.4 shows a general form of the phase diagram.

170  Step 4. Review the Knowledge You Need to Score High

Unit cell

Figure 12.1 The crystal lattice for a simple cubic unit cell.

Figure 12.2 The three types of unit cell of the cubic lattice.

Simple cubic Body-centered cubic Face-centered cubic