Key stage 3 chemistry

• All substances, solid, liquid or gas are made from atoms
• Atoms can bond together to form molecules
• The simplest substances are made from one type of atom-they are called elements
• Elements can chemically combine in a chemical reaction to make compounds.
• Mixtures are substances that have not reacted.
• Solutions are a special type of mixture made of a solvent and a solute(dissolved in the solvent)
• Solid particles are: close together, held in a fixed position, in a regular pattern and cannot move around (can only vibrate to and fro)
• Liquid particles are: close together(slightly further apart than in a solid), free to move around and move faster than those in a solid
• Gas particles are: spaced apart meeting that are able to compress and move very quickly at great speeds
• This is an example of a solid

  
• This is an example of a liquid

  
• This is an example of a gas

  
• If a solid changes into a liquid then it is melting
• If a liquid changes into a solid then it is freezing
• If a liquid changes into a gas then it is evaporating
• If a gas changes into a liquid then it is condensing
• A compound is a substance made of 2 or more elements that are chemically combined
• Every substance has a formula ( plural: formulae
• Solute: a substance that has dissolved
• Solvent: a liquid that dissolves a substance
• Solution: a liquid that has a substance dissolved in it
• Soluble: a substance that can be dissolved
• Insoluble: a substance that cannot be dissolved
• If you keep adding sugar to water until no more can be dissolved, then the solution is saturated
• When sugar and water are mixed, the water particles get between the sugar particles and separate them. The separated particles are too small to be seen, which is why the solution looks clear.
• Filtration is used to separate an insoluble solid from a liquid
• Evaporation is used to separate a dissolved solid from a solution
• Distillation is used to separate pure liquid from a solution