Chemical reactions

• Solid


  Particle diagram of a solid
• Compound


  Different elements held together by chemical bonds
• Mixture


  Substances physically combined but not chemically combined
• Chemical reaction


  A change in which atoms are rearranged to create new substances. Atoms are joined together in 1 way before reaction and in a different way after reaction
• What all chemical reactions do

  • Make new substances
  • Transfer energy to or from surroundings
• Useful chemical reactions


  • Burning petrol to fuel cars
  • Burning coal for electricity
  • Making paracetamol
  • Creating fabrics, like polyester
  • Mixing cement
• Not useful chemical reactions

  • Rust
  • Rotting food
• Catalysts


  • Used to speed up reactions
  • Specific to the reaction
  • Not used up (so they can be used over and over again)
• Catalyst


  Used by chemists to speed up slow reactions
• When a chemical reaction takes place

  The atoms have been rearranged into new substances
• When a physical change occurs


  It is easy to get back what you started with
• Signs a chemical reaction is taking place

  • Fizzing or popping noises
  • Heat or another temperature change
  • Sparks or flames
  • A new smell