Chapter12_Fall11

Chapter12_Fall11 - 12 12.1 12.2 12.3 12.4 12.5 12.6 12.7...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Intermolecular Forces and the Physical properties of Liquids and Solids 12 12.1 Intermolecular Forces 12.2 Properties of Liquids 12.3 Crystal Structure 12.4 Types of Crystals 12.5 Amorphous Solids 12.6 Phase Changes 12.7 Phase Diagrams Intermolecular Forces Intermolecular forces are attractive forces that hold particles together in the condensed phases. The magnitude (and type) of intermolecular forces is what determines whether the particles that make up a substance are a gas, liquid, or solid. Gas Liquid Solid Condensed phases Intermolecular Forces Ion-ion (between ions) ܧ , ܨ∝െ Ion-dipole (between ions and molecules) ܧ Dipole-dipole (between molecules) ܧ Hydrogen bonding (type of dipole-dipole force that is especially strong) London dispersion (occurs between all molecules) ܧ Short-ranged repulsions (when molecules or ions get too close, they “bump” into one another and are repelled by strong short-ranged forces) Interaction Energies and Forces that occur between ions and molecules and other ions and molecules.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Intermolecular Forces Permanent dipole moment More on dipoles…. Induced dipole moment is the polarizability and has units of volume . Instantaneous dipole moment δ D ̅ = α E ̅ D ̅ Intermolecular Forces Properties that are affected by the strength of intermolecular forces: Boiling point Vapor pressure Freezing/melting point Surface tension Viscosity Capillary action The magnitude of the attractive forces depends on the magnitude of the dipole. Intermolecular Forces Attractive forces that act between atoms or molecules in a pure substance are collectively called van der Waals forces . Dipole-dipole interactions are attractive forces that act between polar molecules. Intermolecular Forces
Background image of page 2
Hydrogen Bonding Hydrogen bonding is a special type of dipole-dipole interaction. Hydrogen bonding only occurs in molecules that contain H bonded to a small, highly electronegative atom such as N, O, or F. The H atom carries a partial (+) charge that is able to get close to and interact strongly with the partial (-) charge of the N, O or F atom. F H F Hydrogen Bonding Dispersion Forces Dispersion forces or London dispersion forces result from the Coulombic attractions between instantaneous dipoles of non-polar molecules, and are present for all molecules. The strength of the intermolecular dispersion force increases with increasing number of electrons, and is larger when the electrons are easier to polarize (i.e., as the polarizability increases). Intermolecular Forces
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Ion-Dipole Interactions Ion-dipole interactions are Coulombic attractions between ions (either positive or negative) and polar molecules.
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/20/2012 for the course 160 161 taught by Professor Kim during the Fall '08 term at Rutgers.

Page1 / 17

Chapter12_Fall11 - 12 12.1 12.2 12.3 12.4 12.5 12.6 12.7...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online