Liquids and Solids

Red Beryl, Be3Al2Si6O18- Copyright © Houghton Mifflin Company. All rights reserved.

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Figure 16.1: Schematic representation of the three states of matter Copyright © Houghton Mifflin Company. All rights reserved.

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Bubble Pressure The net upward force on the top hemisphere of the bubble is just the pressure difference times the area of the equatorial circle:   The surface tension force downward around circle is twice the surface tension times the circumference, since two surfaces contribute to the force:                                                                          Copyright © Houghton Mifflin Company. All rights reserved.

毛細現象 The height h to which capillary action will lift water depends upon the weight of water which the surface tension will lift:                      The height to which the liquid can be lifted is given by              Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.7: Nonpolar liquid mercury forms a convex meniscus in a glass tube. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.6: A molecule in the interior of a liquid is attracted to the molecules surrounding it, whereas a molecule at the surface of liquid is attracted only by molecules below it and on each side of it. Copyright © Houghton Mifflin Company. All rights reserved.

High T Low T Copyright © Houghton Mifflin Company. All rights reserved.

Low T High T Copyright © Houghton Mifflin Company. All rights reserved.

Classifying Intermolecular Forces Strong ionic attraction Recall lattice energy and its relations to properties of solid. The more ionic, the higher the lattice energy. Intermediate dipole-dipole forces Substances whose molecules have dipole moment have higher melting point or boiling point than those of similar molecular mass, but their molecules have no dipole moment. Weak London dispersion forces or van der Waal's force These forces alway operate in any substance. The force arisen from induced dipole and the interaction is weaker than the dipole-dipole interaction. In general, the heavier the molecule, the stronger the van der Waal's force of interaction. Hydrogen bond Certain substances such as H2O, HF, NH3 form hydrogen bonds,. Metallic bonding Forces between atom in metallic solids belong to another category. Valence electrons in metals are rampant. They are not restricted to certain atoms or bonds. Rather they run freely in the entire solid, providing good conductivity for heat and electric energy. Copyright © Houghton Mifflin Company. All rights reserved.

Strength of Intermolecular Forces Covalent bonds > Hydrogen bonding > Dipole-dipole interactions > London forces                                   400 kcal > 12-16 kcal > 5-0.5 kcal > less than 1 kcal Copyright © Houghton Mifflin Company. All rights reserved.

Dipole-dipole interactions Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16. 2: (a) The electrostatic interaction of two polar molecules Figure 16.2: (a) The electrostatic interaction of two polar molecules. (b) The interaction of many dipoles in a condensed state. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.3: The polar water molecule. Copyright © Houghton Mifflin Company. All rights reserved.

Hydrogen Bonds A covalent bond between -O-H ---- :O- A covalent bond between -N-H----- :O- A covalent bond between F-H ------ :O- A covalent bond between -O-H ---- :N- A covalent bond between -N-H---- :N- A covalent bond between F-H ----- :N- A covalent bond between -O-H ----- :F- A covalent bond between -N-H ---- :F- Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.4: The boiling points of the covalent hydrides of elements in Groups 4A, 5A, 6A, and 7A. Copyright © Houghton Mifflin Company. All rights reserved.

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The phase diagram of water is complex If water behaved more typically as a low molecular weight material, its phase diagram may have looked rather like this: Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.5: An instantaneous polarization can occur on atom a, creating instantaneous dipole. Copyright © Houghton Mifflin Company. All rights reserved.

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What Kinds of Materials Form Liquids at Room Temperature the strength of the bonds between the particles that form the substance (2) the atomic or molecular weight of these particles (3) the shape of these particles Copyright © Houghton Mifflin Company. All rights reserved.

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Molecular Shape -130 36.1 -159.9 27.8 -16.5 9.5 Compound Melting Point (oC) Boiling Point (oC)                                      -130 36.1                 -159.9 27.8              -16.5 9.5 Copyright © Houghton Mifflin Company. All rights reserved.

The Shape of the molecule also matters n-pentane bp= 309.4 k Copyright © Houghton Mifflin Company. All rights reserved.

Categories of Solids Based on the Solid Pack Crystalline solids are three-dimensional analogs of a brick wall. They have a regular structure, in which the particles pack in a repeating pattern from one edge of the solid to the other. Amorphous solids have a random structure, with little if any long-range order. Polycrystalline solids are an aggregate of a large number of small crystals or grains in which the structure is regular, but the crystals or grains are arranged in a random fashion. Copyright © Houghton Mifflin Company. All rights reserved.

Categories of Solids Based on Bonds ionic ........ polar ........ covalent Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.12: Examples of three types of cyrstalline solids. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.8: Several crystalline solids Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.9: Three cubic unit cells and the corresponding lattices. Copyright © Houghton Mifflin Company. All rights reserved.

Crystal Structure Copyright © Houghton Mifflin Company. All rights reserved.

Other structures Copyright © Houghton Mifflin Company. All rights reserved.

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Figure 16.10: X-rays scattered from two different atoms may reinforce (constructive interference) or cancel (destructive interference) one another. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.11: Reflection of X rays of wavelength Copyright © Houghton Mifflin Company. All rights reserved.

A conch shell on a beach. Source: Corbis Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.13: The closet packing arrangement of uniform spheres. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.14: When spheres are closest packed so that the spheres in the third layer are directlly over those in the first layer (aba), the unit cell is the hexagonal prism illustrated here in red. Copyright © Houghton Mifflin Company. All rights reserved.

A toy slide puzzle Copyright © Houghton Mifflin Company. All rights reserved.

A section of a surface containing copper atoms (red) and an indium atom (yellow). Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.15: When spheres are packed in the abc arrangement, the unit cell is face-centered cubic. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.16: The indicated sphere has 12 equivalent nearest neighbors. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.17: The net number of spheres in a face-centered cubic unit cell. Copyright © Houghton Mifflin Company. All rights reserved.

Volume of a unit cell (2r, 4r, r) Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.18: In the body-centered cubic unit cell the spheres touch along the body diagonal. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.19: The body-centered cubic unit cell with the center sphere deleted. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.20: On the face of the body-centered cubic unit cell. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.21: The relationship of the body diagonal (b) to the face diagonal (f) and the edge (e) for the body-centered cubic unit cell. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.22: The electron sea model for metals postulates a regular array of cations in a "sea" of valence electrons. Copyright © Houghton Mifflin Company. All rights reserved.

Grains of nanophase palladium magnified 200,000 times by an electron microscope. Source: Nanophase Technologies Corporation Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.23: The molecular orbital energy levels produced when various numbers of atomic orbitals interact. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.24: A representation of the energy levels (bands) in a magnesium crystal Copyright © Houghton Mifflin Company. All rights reserved.

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Figure 16.25: Two types of alloys Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.26: The structures of (a) diamond and (b) graphite. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.27: Partial representation of the MO energies in (a) diamond and (b) a typical metal Copyright © Houghton Mifflin Company. All rights reserved.

Graphite consitst of layers of carbon atoms. Copyright © Houghton Mifflin Company. All rights reserved.

Figure 16.28: The p orbitals (a) perpendicular to the plane of th carbon ring system in graphite can combine to form (b) an extensive pie bonding network. Copyright © Houghton Mifflin Company. All rights reserved.

Electrical Properties Metallic Conductors, e.g. Cu, Ag... Semiconductors, e.g. Si, GaAs Superconductors, e.g. Nb3Sn, YBa2Cu3O7 Electrolytes, e.g. LiI in pacemaker batteries Piezoelectrics, e.g. a Quartz (SiO2) in watches Copyright © Houghton Mifflin Company. All rights reserved.