> Molecules in motion

Kinetic theory is one of the 'big ideas' in science. All matter is made of atoms (often molecules), but with an enormous variety of arrangements and different motions.

These experiments lead students from the classification of solids, liquids and gases into considering why there is this variety of forms. They might build theories about the atomic structure of matter, guided by the hints given by many experiments. 

Experiment collections Evidence for atoms From crystals to atoms Changes of phase Thermal expansion Physical models for kinetic theory Brownian motion and diffusion Boyle's law Gas laws and absolute zero Molecular speeds Finding the size of atoms Pressure and density of air Mean free path

Guidance Crystals and atomic models for beginners The separation of molecules in a gas Kinetic theory models Equi-partition of energy A simple theory of a gas Brownian motion: facts and myths Making dry ice Estimating the size of a molecule using oil From the pressure law to the Kelvin scale Theoretical thoughts: extrapolation Avogadro's number and the mass of an air molecule Estimate of molecular size: a more formal method