reactivity series

• Reactivity series: metals are arranged from most reactive to least reactive

  • Potassium (K)
  • Sodium (Na)
  • Calcium (Ca)
  • Magnesium (Mg)
  • Carbon (C)
  • Zinc (Zn)
  • Iron (Fe)
  • Lead (Pb)
  • Hydrogen (H)
  • Copper (Cu)
  • Silver (Ag)
• Determining order of reactivity:

  • Reaction of metals with cold water, steam, and dilute hydrochloric acid
  • Reduction of metal oxides with carbon
  • Tendency to form positive ions
  • Displacement of less reactive metals from its salt solution
  • Reduction of the oxide of a less reactive metal
  • Decomposing metal carbonates by heat (thermal decomposition)
  • Difficulty in extracting a metal from its ore
• Metal + water → metal hydroxide + hydrogen

  • Only potassium, sodium, and magnesium (more reactive metals) react with cold water
• Metal + steam → metal oxide + hydrogen

  • Potassium, sodium, and calcium reactions cannot be carried out in labs
• Metal + dilute hydrochloric acid → metal chloride + hydrogen

  • Only metals above hydrogen in the reactivity series react with HCl
  • Exceptions: copper, silver, and lead
• Lead, copper, and silver do not react with cold water, steam, or air

  • Iron reacts slowly with water in the presence of air (rusting)
  • Initial reaction between lead and HCl forms an insoluble layer of lead 2 chloride, preventing further reaction
• Reduction of metal oxides with carbon:

  • Carbon acts as a reducing agent
  • Only metal oxides below carbon can be reduced by carbon
  • Oxides of zinc require the highest temperature for reduction
• Reducing metal oxides with hydrogen:

  • Only metal oxides below hydrogen can be reduced by hydrogen
  • Exceptions: lead and iron can still be reduced by hydrogen
• Heating metal carbonates (thermal decomposition):

  • The more reactive a metal is, the more difficult it is to decompose its carbonates by heat
  • Silver carbonate decomposes into silver and carbon dioxide
• Tendency to form positive ions:

  • More reactive metals have a greater tendency to form positive ions compared to less reactive metals
• Displacement reactions of metals:

  • A more reactive metal displaces a less reactive metal from its salt solution
  • Metal displacement reactions are redox reactions
• Rust prevention methods:

  • Barrier method: painting, oiling/greasing, coating with plastic, tin-plating, chrome-plating
  • Sacrificial protection: galvanizing (zinc plating), attaching a more reactive metal (zinc or magnesium)