chemistry assesment

  • 440

    440 BC- atoms

    the idea of an atom was thought of by Demorcritus and Leucippus. the atom being an indvisable particle that all matter is made of.
  • 1661- earliest ideas of atoms, molecules, and chemical reaction

    Robert Boyle published "The Sceptical Chemist" which was a treatise on the distinction between chemistry and alchemy. It also contained some of the earliest ideas of atoms, molecules, and chemical reaction marking the beginning of the history of modern chemistry
  • 1828- periodic table symbols

    Jakob Berzelius developed a table of atomic weights & introduced letters to symbolize elements. Johann Dobereiner developed groups of 3 elements with similar properties
  • 1864- early version of periodic table

    Lothar Meyer develops an early version of the periodic table, with 28 elements organized by valence. also 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.
  • 1894- nobal gases

    William Ramsay discovered the Noble Gases
  • 1913- periodic law

    Henry Moseley determined the atomic number of each of the elements and modified the 'Periodic Law'.
  • 1940- uranium fission

    Edwin McMillan and Philip H. Abelson identify neptunium, the lightest and first synthesized transuranium element, found in the products of uranium fission.
  • 1940- transuranic elements

    Glenn Seaborg combined transuranic elements.