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Phosphorus was discovered in 1649 by Henning Brand. It was the first element to be chemically discovered.
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In 1864 an English chemist, John Newlands noticed that if the elements were arranged in order of atomic weight, there was a periodic similarity in every 8 elements. He called this the 'Law of octaves'
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In 1869 Lothar Meyer compiled a periodic table of 56 elements that were once again arranged in order of their atomic weight. These elements were based on a repeating pattern of physical properties such as molar volume.
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Also in 1869, Dmitri Mendeleev created a new way of arranging the periodic table. He arranged them on their atomic weight but he left gaps for elements yet to be discovered. Elements with similar properties appeared underneath eachother.
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In 1894, the noble gases were discovered by William Ramsay. He also realised that they represented a new group in the periodic table.
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In 1914 Henry Moseley discovered the atomic number of all of the known elements. He realised that they fit better on the periodic table if they were organised in order of increasing atomic number instead of atomic weight.
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In 1940 Gleen Seaborg artificially produced heavy mass elememts such as neptunium. These were part of a new block of elements called Actinides.
