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All dates have been given to 1st January unless a more accurate date is known.
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John dalton proposed that all matter is made from tiny particles called atoms
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In 1829, Johann Dobereiner started the work that led to his theory of triads. This had him showing that certain groups of 3 elements showed trends in a variety of properties. It worked for Lithium, sodium and potassium, Chlorine , Bromine and Iodine, and a few other sets of elements.
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John Newlands was the first chemist to come up with a table of the elements. He noticed that several properties repeated every eight elements, if they were ordered by atomic weight. He called this the law of octaves. However this only worked for the first few elments, and people did not believe him.
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In 1869, Dmitri Mendeleev pubkished his periodic ttable of all the known elements. He ordered them by atomic weight and suggested that properities repeat periodically. He also left gaps for elements that had not been discovered yet, which was controversial. he also predicted properties for these elements.
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Mendeleev's Ekaaluminium discovered thsi year
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Mendeleev's Ekaboron discovered this year
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Mendeleev's EkaSilcon discovered this year
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J J Thompson discovered that a negatively charged particle of low mass existed. It was called the electron.
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Ernest Ruttherford and his team discovered that atoms have a small, dense region at their centre called the nucleus.
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Niels Bohr first proposed that electrons orbit the nucleus in fixed shells.
