periodic table, history of the

History of the Periodic Table In the 1800’s fifty to sixty of the elements in the current periodic table were already discovered. This prompted the scientist of the time to try to construct a table with all the elements of the time in it. Most of the scientists were trying to construct the table by order of atomic mass or by small groups of similar elements. In 1817 a German scientist, Johann Wolfgang Dobereiner, found that …showed first 75 words of 308 total…

…showed last 75 words of 308 total…Idenry Moseley used x-rays to find the number of protons in an atom. He used this to find the atomic number of atoms. When he found the atomic numbers and placed them on the table it was in the order that Mendeleev put the elements in. This further proved his work. Later on, in the 1950’s, Glenn Seaborg, from the United States, advanced the periodic table by adding the lanthanoid and actinoid series to it.