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Intermolecular Forces and Liquids and Solids

Intermolecular Forces and Liquids and Solids. Chapter 14. Generally, inter molecular forces are much weaker than intra molecular forces!!. Intermolecular Forces. Intermolecular forces are attractive forces. Intramolecular forces hold. Intermolecular vs Intramolecular Forces

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Intermolecular Forces and Liquids and Solids

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  1. Intermolecular Forces and Liquids and Solids Chapter 14

  2. Generally, intermolecular forces are much weaker than intramolecularforces!! Intermolecular Forces Intermolecular forcesare attractive forces Intramolecular forceshold • Intermolecular vsIntramolecular Forces • 41 kJ to vaporize 1 mole of water • 930 kJ to break all O-H bonds in 1 mole of water • “Measure” of intermolecular forces • DHvap • DHsub

  3. Orientation of polar molecules within a solid: Intermolecular Forces Dipole-Dipole Forces Attractive forces between

  4. Ion-Dipole Interaction: Intermolecular Forces Ion-Dipole Forces Attractive forces between an

  5. Intermolecular Forces Dispersion Forces (AKA: London Dispersion Forces) Attractive forces that arise as a result of temporary dipoles induced in ion-induced dipole interaction dipole-induced dipole interaction

  6. Dispersion forces usually increase with Intermolecular Forces Dispersion Forces (continued) Polarizability is the ease with which the electron distribution in the atom or molecule can be distorted • Polarizability increases with: • greater number of • more diffuse

  7. O O S What type(s) of intermolecular forces exist between each of the following molecules? HBr HBr is a polar molecule: dipole-dipole forces. There are also dispersion forces between HBr molecules. CH4 CH4 is nonpolar: dispersion forces. SO2 SO2 is a polar molecule: dipole-dipole forces. There are also dispersion forces between SO2 molecules.

  8. or … … H H B A A A Intermolecular Forces Hydrogen Bond The hydrogen bondis a special dipole-dipole interaction between the hydrogen atom in a polar and an electronegative A & B are N, O, or F

  9. Hydrogen Bond

  10. Liquids • No definite • Definite • Not • Particles are tightly packed together • Condensed state of matter - like solids • Particles are free to slide past one another

  11. Liquids • Unlike a gas, the particles in a liquid are attracted to one another by You know, the ones we talked about…

  12. Properties of Liquids Surface tensionis the amount of energy required to stretch or increase the surface of a liquid by a unit area Strong intermolecular forces =

  13. Properties of Liquids Cohesion is the intermolecular attraction between Adhesion is an attraction between

  14. Properties of Liquids Viscosityis a measure of a fluid’s Strong intermolecular forces =

  15. Evaporation • When liquid molecules have enough kinetic energy to overcome the intermolecular forces holding them together, they may escape the surface of the liquid into the • In any liquid, some particles in the liquid vaporize and produce a

  16. Vapor pressure: a force due to the gas above a liquid • As a liquid is heated its vapor pressure • Volatile: a substance with

  17. Boiling Point • Boiling point is the temperature at which the vapor pressure of a liquid equals the (endothermic!) • At boiling point, liquid turns to gas at within the liquid (bubbling) • Normal boiling point = temperature at which a liquid boils at standard pressure (1 atm or 101.35 kPa)

  18. Water is a Unique Substance Maximum Density 40C Ice is less dense than water Density of Water

  19. Solids • Definite • May expand upon • Molecules tightly packed together • Condensed state of matter along with liquids • Molecules “ ” in place • Due to very strong intermolecular forces holding them together

  20. Melting & Freezing • Melting point: temperature at which solid turns to liquid ( ) • Freezing point: temperature at which liquid turns to solid ( ) • Melting point = freezing point!

  21. Two Main Types of Solids • Crystalline: atoms, ions, or molecules are arranged in an A crystalline solidpossesses rigid and long-range order. In a crystalline solid, atoms, molecules or ions occupy • Shape of crystal depends on • Unit cell: smallest part of a crystal that retains the shape of the crystal.The • Ex: salt, quartz, minerals, & metals

  22. Two Main Types of Solids 2) Amorphous: lack an . Does not possess a well-defined arrangement and long-range molecular order Ex: rubber, plastic, & glass (supercooled liquid).

  23. A glass is an optically transparent fusion product of inorganic materials that has cooled to a rigid state Non-crystalline quartz glass Crystalline quartz (SiO2)

  24. A phase diagram summarizes the pressure and temperature conditions at which a substance exists as a solid, liquid, or gas Phase Diagram of Water

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