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Aristotle discovered the main elements were fire, water, earth and air
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Alchemist used a variety of symbols to identify each element and made many different discoveries to the modern science of chemistry.
e.g. gold (the picture on the left) -
Lavoiser found that mass is conserved in a chemical reaction
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He was best know for the discovery of the law of constant composition which he stated that chemical compounds always combine in constant proportions.
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John Dalton created the very first atomic theory he viewed atoms as tiny, solid balls and had 4 statements for the atomic theory which were: atoms are tiny, invisible particles, atoms of one element are all the same, atoms of different elements are different and compounds form by combining atoms.
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He discovered electrons and was the first scientist to show that the atom was made of even smaller things. He also proposed the existece of positive particles.
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He showed that atoms have positive particles in the centre and are mostly empty space, these positive particles are called protons and the centre of the atom is called the nucleus.
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Chadwick discovered the neutrons he was working with Ernest Rutherford and found out that particles with no charge were called neutrons which were located in the nucleus.
