Significant Events in the Periodic Table

1. Alexandre Béguyer de Chancourtois was a French Geologist who made significant headway in the development of the periodic table. His most renown contribution was the ‘vis tellurique’ which in English is the telluric screw. The telluric screw is a three dimensional figure which arranged the elements in ascending order of their atomic number. Although the telluric screw wasn’t completely accurate, it was the first ever arrangement made with all known elements and it showed that similar elements appeared at periodic atom weights.

1. John Newlands, in 1864, proposed The Law of Octaves which was inspired by the octaves of music. Using this law, he suggested that there were noticeable physical and chemical similarities for every 8 elements. Although, during the time period, noble gases weren’t discovered yet so Newlands didn’t leave any gaps in his table causing him to have to put two elements in one box to maintain the pattern. To the Chemical Society, this seemed incorrect making his work unable to be published.

1. Julius Lothar Meyer, in 1868, made a more organised and developed table. The first table that he made only included 28 elements which were ordered by their atomic number but in 1868, he created a table which included the transition metals and almost all the main groups. He also included elements being in the same column if they had equal valences

1. Dimitri Mendeleev discovered the periodic table while attempting to organise the elements in February, 1869. To do so, he wrote the properties of the elements on cards and arranging them by putting them in order of their atomic weight. By doing this, he realised that by putting them in order, specific element types continuously occurred. He also left spaces for soon to be discovered elements.

Henry Mosely, in 1914, found a way to measure a property that linked perfectly to periodic table placement. Using an electro gun, he was able to fire a line of electrons at different element samples. By doing so, he found that different elements give off a certain X-ray. He then measured the frequency of the element and realised that the frequency of the X-ray was linked to the positioning of the element on the Periodic Table. The atomic number was actually measurable!

1. In 1940, Glenn T. Seaborg paired up with Edwin McMillian, Joseph Kennedy and Arthur Wahl isolated plutonium and in 194, they isolated Uranium. This allowed them to establish thorium’s nuclear fuel potential. He created the first eleven transuranium elements, which would be part of the transition metals.