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Development of the Periodic Table - Coggle Diagram
Development of the Periodic Table
Alexandre-Emile Béguyer de Chancourtois
De Chancourtois was responsible for introducing the "vis telluric", more commonly known as the telluric screw.
The telluric scres plotted the atomic weights of the elements outside of a cylinder. This meant that one turn would result in an atomic weight increase of 16.
However, the telluric screw did not correctly display all the trends that were known at the time.
John Newlands
4 years before Mendeleev announced his periodic table, Newlands found out that there were several similarities between elements with atomic weights that differed by 7.
John Newlands called this the Law of Octaves, where he drew a comparison with the octaves in music, which are 7 notes apart.
The noble gases were not discovered until much later, which explains why there was a periodicity of 7 and not 8 in John Newlands' table.
Unlike Medeleev, John Newlands did not leave gaps for elements in his table, and often had to cramm 2 elements into a box to keep the pattern.
Julius Lothar Meyer
Meyer's first table contained just 28 elements, which were organised by their valency, which was how many other atoms it can be combined with.
These elements were almost entirely the main group elements, but in 1868 he incorporated transition metals in a much more developed table.
This table listed the elements in order of atomic weight, which the elements with the same valency arranged in vertical lines, which was similar to Mendeleev's table.
Unfortunately for Meyer, his table wasn't published until 1870, which was a year after Mendeleev published his periodic table.
Dmitri Mendeleev
Dimitri Mendeleev was not the first to attempt at finding order within the elements, but his attempt was so successful that it is the basis of the modern periodic table.
Mendeleev discovered the periodic table while attempting to organise the elements in February of 1869.
The did this by writing the properties of the elements on pieces of card and rearranging them until he realised that putting them in order of increasing atomic weight, certain types of element regularly occured.
He originally organised them horizontally, but realised that it was easier to organise it vertically.
Henry Mosely
Henry Mosely was the person who found out that Mendeleev's periodic table was arranged according to atomic amss.
With the newly discovered X-ray gun, he fired it at samples of elements, and measured the wavelength of the X-rays given.
He used this to calculate the frequency and found that when the square root of the frequency was plotted against an element's atomic number, the graph showed a perfectly straight line.
Within 10 years of work, the structure of the atom had been determined through the work of many prominent scientists of the day, explaining further why Moseley's X-rays corresponded so well with atomic number.
The amount of energy that is given out depends on how strongly the electrons were attracted to the nucleus.
After years of searching, we had a periodic table that really worked, and the fact that we still use it today is a testament to the huge achievement of these and many other great minds