Periodic Table

  • 330

    Aristotle propses element theory

    Aristotle proposes the four element theory: earth, air, fire & water
  • 400

    Democritus proposes the atom

    400 BC Democritus and Leucippus propose the idea of the atom, an indivisible particle that all matter is made of.
  • First list of elements

    Antoine Lavoisier wrote the first extensive list of elements containing 33 elements & distinguished between metals and non-metals
  • First periodic table

    Jakob Berzelius developed a table of atomic weights & introduced letters to symbolize elements
  • Mendeleev's table

    Dmitri Mendeleev produced a table based on atomic weights but arranged 'periodically' with elements with similar properties under each other. His Periodic Table included the 66 known elements organized by atomic weights.
  • Radioactivity

    Ernest Rutherford discovered the source of radioactivity as decaying atoms
  • Periodic Law

    Henry Moseley determined the atomic number of each of the elements and modified the 'Periodic Law'