The development of the periodic table

• Periodic table


  Arrangement of elements based on their properties
• Development of the periodic table

  1. John Newlands arranged elements in order of atomic weight

  2. Noticed periodicity (repeated patterns)

  3. Missing elements caused problems

  4. Dimitri Mendeleev realised some elements were yet to be discovered

  5. Left gaps in table for undiscovered elements

  6. Reordered some elements

  7. Placed elements in vertical columns based on similar properties

  8. Used periodic table to predict existence and properties of new elements

  9. Organised elements in order of increasing atomic number (number of protons)
• In 1864, only 63 elements were known, many were still undiscovered
• Strictly following the order of atomic weight created issues, as it meant some elements were in the wrong place
• When the subatomic particles were later discovered, it revealed that Mendeleev had organised the elements in order of increasing atomic number (number of protons)