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Antoine Lavoisier
*Grouped the elements based on their properties into gases, non-metals, metals and earths. -
Johann Döbereiner
Recognised triads of elements with chemically similar properties, such as lithium, sodium and potassium, and showed that the properties of the middle element could be predicted from the properties of the other two. -
Karlsruhe Conference
A more accurate list of the atomic mass of the elements became available at a conference in Karlsruhe, Germany. that was when real progress was made -
Alexandre Béguyer de Chancourtois
*Was the first to use a periodic arrangement of the elements
* Invented the telluric screw that plotted the atomic weights of the elements on the outside of a cylinder, so that one complete turn corresponded to an atomic weight increase of 16. -
John Newlands
Noticed similarities between elements with atomic weights that differed by seven.
The Law of Octaves -
Julius Lothar Meyer
Created a table that listed the elements in order of atomic weight, with elements of the same valency arranged in vertical lines. -
Dmitri Mendeleev
Discovered the periodic table, while attempting to organise the elements. He realised that by arranging them in order of increasing atom weight, certain types of element regularly occured. Mendeleev arranged the elemnts in the correct way, and if the elment appeared in the wrong spot he moved it to where it should go. Mendellev left gaps for undiscovered elements and even predicted some elemnts that had not been found then. -
Henry Moseley
Mendellev had seen that some elements needed swapping around but it was Moseley that determined why. He fired the newly-developed X-ray gun at samples of the elements, and measured the wavelength of X-rays given. He used this to calculate the frequency and found that when the square root of this frequency was plotted against atomic number, the graph showed a perfect straight line. He’d found a way to actually measure atomic number.
