1. Solids and Phase Changes

2. Properties of Solids Molecules are tightly packed
All IMF forces exert stronger effects in solids
Forces hold particles in fixed positions
Only vibrational movement around fixed points
More order of particles due to stronger IMFs.

3. Types of Solids Crystalline—consist of crystals
Crystal—particles are arranged in a orderly, geometric, repeating pattern.
Amorphous—particles are arranged randomly.

4. Properties of Solids Definite shape and volume
Crystalline solids—particles packed into crystal lattice
Amorphous—when broken, maintain a definite shape but do not exhibit a distinct geometric shape.
Glass—after being molded, shatters in irregular shapes

5. Properties of Solids Definite Melting Point for crystalline solids
Melting—solid changes phase to a liquid by addition of energy as heat.
Melting point—temperature at which solid becomes liquid
KE of particles overcomes attractive forces
Amorphous solids = no definite melting point
Flow over range of temps
Particles are arranged randomly like a liquid.

6. Properties of Solids High incompressibility High density
Low rate of diffusion—millions of times slower than liquids or gases.

7. Crystalline Solids
Crystal structures—used to show arrangements of particles in a crystal lattice.
Unit cell—shows smallest unit of the repeating pattern of entire crystal

8. Crystalline Solids 4 types Ionic
Contains positive and negative ions in a repeating pattern.
Hard, brittle, high MP, good insulators
Ex. MgCl2

9. Crystalline Solids Covalent network
Each atom is covalently bound to the neighboring atom
Hard, brittle, nonconductors or semiconductors
Ex. SiO2, Graphite, Diamond,

10. Crystalline Solids Metallic Metals held together by sea of electrons
Covalent molecular
Individual molecules held together by IMFs
Low MP, soft, good insulators

11. Phase Changes

12. Changes of State
Phase change—any change from one state of matter to another.
Requires energy transfer to occur
Energy flows from higher energy particles to lower energy particles.
Intermolecular forces (IMF’s) are also affected.

13. Processes that take energy
Melting—changing from a solid to a liquid state
Energy change?
IMF’s?
Sublimation—change of state from a solid directly to a gas.
Vaporization—change of state from a liquid to a gas.

14. Phases releasing energy
Condensation—gas changes to liquid state
Energy change?
IMF’s?
Deposition—gas goes directly to a solid
Same process as condensation, except on much cooler surfaces
Freezing—liquid to solid

15. Equilibrium
Condition in which two opposing changes occur at equal rates in a closed system.

16. Phase Diagrams
Phase diagram—graph in which pressure versus temperature is used to show the conditions of phase changes for a specific substance.
Triple Point—point at which all three states of matter coexist.
Critical point—point of critical temp and critical pressure.
Critical temp—temperature above which the substance cannot exist as a liquid
Critical pressure—lowest pressure that substance can exist as a liquid.