1 Types of Solids Chap. 13: Day 4b

2 Metallic and Ionic Solids Sections

3 Properties of Solids Molecules, atoms or ions locked into a CRYSTAL LATTICE 2. Particles are CLOSE together 3. STRONG IM forces 4. Highly ordered, rigid, incompressible ZnS, zinc sulfide

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5 Types of Solids Table 13.6 TYPE FORCE Properties. Ionic Ionic Hard, brittle, High MP poor conductor poor conductor Metallic Electrostatic Malleable, Range of MP good conductor good conductor Molecular Dipole Soft, Low of MP Ind. Dipole poor conductor Ind. Dipole poor conductor NetworkExtended Range of MP & hardness covalent poor conductor covalent poor conductor

6 Network Solids Diamond Graphite

7 A comparison of diamond (pure carbon) with silicon.

8 Atom Packing in Unit Cells Assume atoms are hard spheres and that crystals are built by PACKING of these spheres as efficiently as possible.

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PROPERTIES OF LIQUIDS Chap. 13: Day 4a

Intermolecular Forces The forces BETWEEN molecules. Holds the molecules together. At a set temperature: What phase has the strongest force? Solids What phase has the weakest forces? Gases (vapor)

Viscosity the resistance of a fluid to flow Thick fluids have high viscosity

Liquid Properties Surface Tension- Ability of liquid molecules to hold on to each other. Apparent “skin” affect Ex. Over filling a liquid in a glass with out the liquid spilling

Hg

Liquid Properties Capillary Rise- the tendency of a liquid to rise in a small diameter tube due to the surface tension of the liquid.

Vapor Pressure The pressure exerted by a vapor in equilibrium with its liquid state. The pressure at which liquid changes to vapor Liquids with high vapor pressures turn into vapors very easily. (Volatile) Ex. Gasoline, perfume

Once equilibrium is reached, the vapor particles will begin to condense back to a liquid

Boiling Point The temperature at which the vapor pressure of the liquid equals the atmospheric pressure The entire liquid is changing state, not just the surface. Water boils at C at standard P

Vapor Pressure vs Temperature

24 TWO ways to change PHASE Temperature Pressure PHASE CHANGES:

25 Al melting points SOLID LIQUID

26 Boiling points: Liquid to Vapor Water LIQUID GAS

27 Phase Diagrams

28 TRANSITIONS BETWEEN PHASES Section Lines connect all conditions of T and P where EQUILIBRIUM exists between the phases on either side of the line. (At equilibrium particles move from liquid to gas as fast as they move from gas to liquid, for example.)

29 Phase Equilibria — Water Solid-liquid Gas-Liquid Gas-Solid

30 Triple Point — Water At the TRIPLE POINT all three phases are in equilibrium.

31 Phases Diagrams— Important Points for Water T(˚C)P(mmHg) Normal boil point Normal freeze point0760 Triple point

32 Critical T and P Above critical T no liquid exists no matter how high the pressure. As P and T increase, you finally reach the CRITICAL T and P

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34 Critical T and P T c ( o C) P c (atm) M ( g/mol ) T c ( o C) P c (atm) M ( g/mol ) H 2 O (18) P Freon (121) NP (CCl 2 F 2 ) CO (44) NP CH (16) NP Notice that T c and P c depend on intermolecular forces.

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37 Phase Diagram for Water

38 Solid-Liquid Equilibria Raising the pressure at constant T causes water to melt. The NEGATIVE SLOPE of the S/L line is unique to H 2 O. Almost everything else has positive slope.

I NTERMOLECULAR F ORCES STRONG Forces lead to…. Nonvolatile Substances High boiling points Low evaporation rates Low vapor P at room temperature WEAK Forces lead to..  Volatile substances  Low boiling points  High evaporation rates  High vapor P at room temperature