Chemistry: Chemical Changes: Key terms

• Oxidation

  when a species loses electrons
• Reduction


  when a species gains electrons
• Reactivity series


  a list in which elements are placed in order of how reactive they are
• Displacement reaction


  a reaction in which a more reactive metal displaces a less reactive metal from a solution of its salt
• Extraction


  the process of obtaining / taking out / removing, e.g. obtaining a metal from an ore or compound
• Dissociate


  to split up into ions
• Aqueous


  dissolved in water
• Indicator


  a chemical that is one colour in an acid and another colour in an alkali
• Neutralisation


  occurs when an acid reacts with exactly the right amount of base
• Strong acid


  an acid, such as hydrochloric acid, nitric acid or sulfuric acid, that is completely ionised in water
• Ionised

  split up into ions
• Weak acid


  an acid, such as ethanoic acid, citric acid or carbonic acid, that is only partially ionised in water
• Electrolysis


  the process by which an ionic compound is broken down into its elements using an electrical current
• Electrolyte

  the substance being broken down during electrolysis
• Electrode

  an electrical conductor used in a cell
• Anode

  a positively charged electrode
• Cathode

  a negatively charged electrode
• Cryolite

  a compound of aluminium