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Robert Boyle suggested that an element was a substance that cannot be broken down any further by chemical reaction. He wrote two books on chemistry (New Experiments Physico-Mechanicall, Touching the Spring of the Air, and Its Effects) and the second,(New Experiments Physico-Mechanicall, Touching the Spring of the Air, and Its Effects Second edition) was where he discussed the elements.
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Antoine Lavoisier made a detailed list of substances that he believed to be elements. He had 33 elements in his table.He recognised and named oxygen (1778) and hydrogen (1783) and opposed the phlogiston theory.
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Jakob Berzelius used symbols to do with the name of the chemical to make it easier to identify them. he also used the weight of hydrogen to develop a coherent system of atomic weights.
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Johann Döbereiner was awar of 40 elements in1829. he noted that some groups of three had similar properties and named these groups triads
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John Noted that every eighth element had similar properties. He named it the 'law of octaves'.
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William Ramsay separated the components of air.he identified: helium, neon, argon, krypton and xenon. all these gasses are called noble gasses.
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Henry refined the order of some of the elements in mendeleevs periodic table and proposed a minor change to the periodic law: 'elements have properties that recur according to their atomic number.'
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glenn Seaborg used a cyclotron to slam neutrons into uranium atoms. this created the very first atoms of neptunium and plutonium. he later discovered: americium, curium, berkelium, californium, einsteinium etc.
