Comparison of Gases, Liquids and Solids Property\State Gas Liquid Solid Intermolecular Interaction Virtually none Considerable interaction Flow Fluid – free flow Fluid – nearly free flow Rigid – virtually none Actual/Occupied Volume Ratio Close to Negligible Slightly<1.00 Mode of Motion Virtually random translational motion Restricted translational motion Vibration about fixed sites only Simple Equation of State Yes No

Phase Changes

Dipole-Dipole Forces

Ion-Dipole Forces

Formation of Induced Dipole in a Helium Atom No induction in (a), since there are no ions or polar molecules in close proximity. Induction in (b) due to presence of near ion or polar molecule

Induced Dipoles in Helium The induced dipoles exist only momentarily. Nevertheless, at low enough temperatures, the generated dispersion forces are sufficient for helium to condense.

Hydrogen Bonds in Water

Surface Tension

Capillary Action (a) Adhesion is higher (b) Cohesion is higher

Unit Cell and 3-D Depiction 3-D Structure

Seven Types of Units Cells – Seven Crystal Systems

Packing of Spheres – Simple Cubic Cell

Packing of Spheres – Body Centred Cubic Cell

Closest Packing – Two Arrangements

Cubic Unit Cells

Radii and Edge Length Relationships for Cubic Cell

X-Ray Diffraction

Crystal Structure of NaCl

Diamond and Graphite – Covalent Crystals

Properties of Crystals

Vapour Pressure

Vapour Pressure - Temperature

A Typical Heating Curve

Phase Diagrams