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Robert Boyle defined an element as a substance that cannot be broken down into a simpler substance by a chemical reaction. This defintion has actually served for over 300 years and is still being taught to introductory chemistry classes.
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A German merchant and amateur Alchemist Hennig Brand attempted to create an object that could turn metals into gold. He wasn't successful however this led to the accidental discovery of phosphorus.
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Hydrogen was first discovered by Henry Cavendish. Hydrogen is described to be as a gas that is colourless and odourless that can explode with certain mixtures with air.
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Carl Willhelm and Joseph Priestly were able to separate and isolate oxygen leading to it's discovery.
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During this time 47 elements were discovered and scientists were able to identify similar characteristics within those elements.
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Jakob Berzelius introduced letters to symbolize the elements on the periodic table.
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German chemist Johann Dobereiner grouped elements by threes and would be ordered according to their atomic weight.
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John Newlands divided the 56 elements into 11 groups based on their characteristics.
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The first Periodic Table was published by Dmitri Mendeleev, he arranged the elements by their atomic mass whilst predicting other elements to be discovered leaving some spaces for them.
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Sir William Ramsay and Lord Rayleigh discovered noble gases which were then added to the periodic table known as group 0.
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Henry Moseley was able to identify the atomic number for the elements, with this in mind the periodic table was then rearranged according to the atomic number.
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James Chadwick discovers neutrons and isotopes in which then became the basis for the periodic table.
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Glenn Seaborg identified lanthanides and actinides which are placed at the bottom of the periodic table.