chemistry

Chapter 1: Intermolecular
Forces: Liquids, Solids, and Phase Changes
Chem 11: General Chemistry 2

Topics
1.1 An Overview of Physical States and Phase
Changes
1.2 Quantitative Aspects of Phase Changes
1.3 Types of Intermolecular Forces
1.4 Properties of the Liquid State
1.5 Uniqueness of Water
1.6 The Solid State: Structure, Properties and
Bonding



A hot spring on a snowy day

The Kinetic Molecular View of the Three
States


The characteristic properties of gases, liquids, and solids can be understood in terms of the energy of motion (kinetic energy) of particles
(atoms, molecules and ions) of each state compared to the energy of the intermolecular interactions between particles.

The Kinetic Molecular View of the Three
States


The state of a substance depends largely on the balance between the kinetic energies of the particles and the interparticle energies of attraction. 



Kinetic energies – tend to keep the particles apart and moving
Interparticle attractions – tend to draw the particle together.

The Kinetic Molecular View of the Three
States



In a solid , the interparticle attractions dominate the kinetic energy so that the particles remain in position relative to one another. 

With the fixed position of particles, solid has


specific shape



less compressible than liquids

The Kinetic Molecular View of the Three
States



In a liquid , the attractions are stronger than motion because the particles are in virtual contact.



But their kinetic energy still allows them to tumble randomly over and around each other.



Liquid resist an applied external force.

The Kinetic Molecular View of the Three
States



In a gas , the energy of attraction is small relative to the energy of motion; so on average, the particles are far apart.



A gas moves randomly throughout its container and fills it.



Gases are highly compressible, and they