Memory Anchor:

• Draw a labelled diagram to show the particle arrangement for a material sample as a solid, liquid and gas. Like:
• http://www.chemistry.wustl.edu/~edudev/LabTutorials/Thermochem/images/SolLiqGas.jpg
• Check for number of particles being constant.
• Label melting, freezing, evaporation, sublimation, condensation.

Super Challenge:

Stretch:

Challenge:

Key Questions:

1. How does the mass of water change as an ice cube melts?
   • The mass of water stays the same as an ice cube melts.
2. What does the term 'conservation of mass' mean?
   • Particles can not be created or destroyed.
3. Why does the mass change during evaporation?
   • Although there are no Particles destroyed during evaporation, once a gas the Particle can not be measured by the balance.
4. How can we represent the changes of state in diagram form?
   • Check for number of Particles being constant; Label melting, freezing, evaporation, sublimation, condensation.