Development of the Periodic Table - Matthew Samson 10WO

By MSamson

  • Definition of an element

    Robert Boyle defined an element as a substance that cannot be broken down into a simpler substance by a chemical reaction. This defintion has actually served for over 300 years and is still being taught to introductory chemistry classes.

  • Discovery of Phosphorus

    A German merchant and amateur Alchemist Hennig Brand attempted to create an object that could turn metals into gold. He wasn't successful however this led to the accidental discovery of phosphorus.

  • Discovery of Hydrogen

    Hydrogen was first discovered by Henry Cavendish. Hydrogen is described to be as a gas that is colourless and odourless that can explode with certain mixtures with air.

  • Discovery of Oxygen

    Carl Willhelm and Joseph Priestly were able to separate and isolate oxygen leading to it's discovery.

  • 47 elements are discovered

    During this time 47 elements were discovered and scientists were able to identify similar characteristics within those elements.

  • Elements represented as letters

    Jakob Berzelius introduced letters to symbolize the elements on the periodic table.

  • Law of Triads

    German chemist Johann Dobereiner grouped elements by threes and would be ordered according to their atomic weight.

  • 56 elements, 11 groups

    John Newlands divided the 56 elements into 11 groups based on their characteristics.

  • The First Periodic Table

    The first Periodic Table was published by Dmitri Mendeleev, he arranged the elements by their atomic mass whilst predicting other elements to be discovered leaving some spaces for them.

  • Discovery of noble gases

    Sir William Ramsay and Lord Rayleigh discovered noble gases which were then added to the periodic table known as group 0.

  • Periodic table arranged by atomic number

    Henry Moseley was able to identify the atomic number for the elements, with this in mind the periodic table was then rearranged according to the atomic number.

  • Neutrons are discovered

    James Chadwick discovers neutrons and isotopes in which then became the basis for the periodic table.

  • Lanthanides and Actinides

    Glenn Seaborg identified lanthanides and actinides which are placed at the bottom of the periodic table.