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In 440 B.C.E, a greek philosopher named Democritus hypothesized that all matter is able to breakdown into tiny invisble particles until they can not break down any more but his idea wasn't popular because there was no experminatal evdience.
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Aristotle belived that all matter was made up of four elements: fire, water, air and earth.
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In 1677 C.E he discovered many theories and laws that has helped us understand the universe and has helped our scientists to discover how to enter space. He discovered gravtiational force and the 3 universal laws of motion.
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He helped develop a definition for the atomic theory and helped with the four elements: fire,water,air and earth.
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He discovered a gas named oxygen.
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In 1700s C.E. a french nobleman named Anotine Lavoisier had recognized and named oxygen and hydrogen and contributed in the metric system.
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John Dalton recognized the idea that each elements is compound of a different atom.
1.) All matter is broken into particles called atom
2.) Atom of different elements have different properties
3.) Atoms of different elements can be combined to create different substances
4.) Atoms of an element are identical in properties such as size and mass -
He conducted an experiment where he shot positively charged particles through tin foil which then made a timy hole. Using this, he discovered inside the atom had to be a nucleus.
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In 1897 Thomson stated that atoms might be are made from a combination of particles that are charged. Atoms must be both positive protons and negative electrons.
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James Chadwick discovered that the nucleus contained neutral particles called neutrons and postitively charged particles called protons.
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Niels Bohr suggested that electrons surrounded the nucleus in energy levels known as shells and that they jumped between these shells.
