Periodic table

Organizing the Periodic table

  • Antoine Lavoisier published a list of 33 chemical elements

    The first organization of the elements was published by Antoine Lavoisier in 1789 . The published a list of 33 chemical elements grouped into gases, metals, nonmetals and earths. Among elements that we recongize such as oxygen and zinc, Lavoisier also included light and caloric, which he believed to be material substances.
  • Johann Wolfgang Dobereiner observed that many of the elements could be grouped into triads based on their chemical properties.

  • August Kekule observed that Carbon has a tendency to bond with other elements one to four.

    This concept became known as valency.
  • Julius Lothar Meyer published a table of the 49 known elements arranged by valency

    This table revealed that elements with similiar properties often shared the same valency.
  • Dmitri Mendeleev published his periodic table that listed elements by increasing atomic weight.

  • Gallium was discovered.

    The discovery of gallium corresponded exactly to a value Mendeleev had assigned to a gap in his table directly below Aluminum. This helped prove Mendeleev's table.
  • Scandium was discovered

    This filled a gap between Calcium and Titanium in Mendeleev's table.
  • Period: to

    Nobel Gases are discovered

    The discovery of the noble gases upset Mendeleev's table because he had not accounted for a complete column missing from his table.
  • Mendeleev's Death

  • Henry Mosley reorganized the table by atomic number

    Atomic number was discovered through the use of X-Rays and the table was reorganized by atomic number.
  • Mendelevium discovered

    Mendelevium was named after Dmitri Mendeleev.