Copyright © Houghton Mifflin Company. All rights reserved. 16a–1

Copyright © Houghton Mifflin Company. All rights reserved. 16a–2 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: bubble pressuresurface tension

Copyright © Houghton Mifflin Company. All rights reserved. 16a–3 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 weight 毛細現象

Copyright © Houghton Mifflin Company. All rights reserved. 16a–4 High T Low T

Copyright © Houghton Mifflin Company. All rights reserved. 16a–5 Low T High T

Copyright © Houghton Mifflin Company. All rights reserved. 16a–6 Classifying Intermolecular Forces 1.Strong ionic attraction Recall lattice energy and its relations to properties of solid. The more ionic, the higher the lattice energy. 2.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. 3.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. 4.Hydrogen bond Certain substances such as H 2 O, HF, NH 3 form hydrogen bonds,. 5.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. 16a–7 Covalent bonds > Hydrogen bonding > Dipole-dipole interactions > London forces 400 kcal > kcal > kcal > less than 1 kcal Strength of Intermolecular Forces

Copyright © Houghton Mifflin Company. All rights reserved. 16a–8 Dipole-dipole interactions

Copyright © Houghton Mifflin Company. All rights reserved. 16a–9 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- Hydrogen Bonds

Copyright © Houghton Mifflin Company. All rights reserved. 16a–10

Copyright © Houghton Mifflin Company. All rights reserved. 16a–11

Copyright © Houghton Mifflin Company. All rights reserved. 16a–12

Copyright © Houghton Mifflin Company. All rights reserved. 16a–13 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. 16a–14 What Kinds of Materials Form Liquids at Room Temperature (1)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. 16a–15

Copyright © Houghton Mifflin Company. All rights reserved. 16a–16 Molecular Shape CompoundMelting Point ( o C)Boiling Point ( o C)

Copyright © Houghton Mifflin Company. All rights reserved. 16a–17 The Shape of the molecule also matters n-pentane bp= k

Copyright © Houghton Mifflin Company. All rights reserved. 16a–18 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. 16a–19 Categories of Solids Based on Bonds ionic polar covalent

Copyright © Houghton Mifflin Company. All rights reserved. 16a–20 Crystal Structure

Copyright © Houghton Mifflin Company. All rights reserved. 16a–21 Other structures

Copyright © Houghton Mifflin Company. All rights reserved. 16a–22

Copyright © Houghton Mifflin Company. All rights reserved. 16a–23 Sodium chloride crystals are brittle Structure of NaCl: an ionic crystal Why 6-coordinated ?

Copyright © Houghton Mifflin Company. All rights reserved. 16a–24 Grains of nanophase palladium magnified 200,000 times by an electron microscope. Source: Nanophase Technologies Corporation

Copyright © Houghton Mifflin Company. All rights reserved. 16a–25 Electrical Properties Metallic Conductors, e.g. Cu, Ag... Semiconductors, e.g. Si, GaAs Superconductors, e.g. Nb 3 Sn, YBa 2 Cu 3 O 7 Electrolytes, e.g. LiI in pacemaker batteries Piezoelectrics, e.g. a Quartz (SiO 2 ) in watches