development of periodic table

• John Newlands

  • arranged in order of their relative atomic weights (now atomic masses)
  • 1865, he suggested that rather than being in triads, elements show similar properties to the element eight places after in the table, naming it the law of octaves
• Dmitiri Mendeleev

  • 1869, he published the modern periodic table which is similar to Newlands
  • elements with similar properties were arranged in vertical columns
  • gaps were left where no element fitted the repeating patterns, and properties of the missing elements were predicted + later found