• substances contain particles rather than consist of particles, e.g. pupils think water has particles in it, with water or air between the particles, pupils think that air has oxygen particles in it and there is air between the particles
  
• particles are comparable in size to cells, dust specks, etc., and they can be seen with an optical microscope
  
• particles of the same substance have different properties in solid, liquid or gas state, e.g. some pupils think solid ice particles are cold and hard, liquid water particles have expanded and so they are larger and softer, while water vapour particles expand even more and are very large and squashy
  
• all liquids contain water
  
• air is good (breathing) and gas is bad (flammable or poisonous)
  
• gases have no weight, or even have negative weight, and that is why things filled with gas float
  
• when water evaporates it splits up into atoms of hydrogen and oxygen
  
• the bubbles in a boiling liquid are bubbles of air
  
• melting and dissolving are the same
  
• boiling points are not fixed and the temperature will continue to go up as more energy is transferred
  
• condensation forms as a result of the ‘cold' causing oxygen and hydrogen in the air to make water
  
• atoms are a small bit of the parent material with all the same properties as that material
  
• the proportions of combining elements in a compound are not fixed
  
• metallic properties are due to properties of the atom rather than the atomic arrangement
  
• non-metals are substances such as sugar or wood rather than non-metallic elements
  
• chemical change is what is observed during the reaction, e.g. fizzing, not the production of a new substance.

Pupils are often confused or uncertain about: