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Democritus was a greek philosopher. He lived between the years 470-380 B.C. He believed that everything was made up of small microscopic and indestructible atoms meaning invisible in greek. He laterproved his theory, although he thought it was just a microscopic ball with nothing inside it.
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Aristotle didn' agree with Democritus. Aristotle believed that there were only four elements; earth, water, fire and air. He thought that these elements had atoms that made up all the other matter on Earth.
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He was a Irish physicist and chemist, which lived from 1627-1691. Robert Boyle defined the word element. He agreed with Democritusand not Aristotle. Because of the nature of gases, he believed in the corpuscular theory, which meant that he belived the air was made of particles.
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Isaac Newton believed that small solid masses were in motinon in the mechanical universe.
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Joseph Priestley was born in Leeds, Great Britain on March 3, 1733 B.C. He discoverd eight different elements/gases.
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He discovered that water is made up of hydrogen and oxygen. He proposed the Combustion Theory which was based on sound mass measurements. He named oxygen. He also proposed the Law of Conversation of Mass which represents the beginning of modern chemistry.
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He lived between 1754 and 1826. Law of Definite Proportions (or Law of Constant Composition) in 1794. This law is basically a law that states that a compound is composed of exact proportions of elements by mass.
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(1776-1844) He created symbols to represent atoms of different elements. Dalton recognized the existence of atoms of elements and that compounds formed from the union of these atoms.
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Michael Faraday began to realize the importance of electrical forces in compounds. He found out that electrical forces held atoms together.
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(1779-1848) He developed the concepts of the ion and ionic compounds. He analyses, and collected data on the relative weights of atoms of 43 elements. He introduced the symbolism
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Hantaro Nagaoka showed an atomic model called the Saturnian Model to describe the structure of an atom.
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He was born in Neustadt-an-der-Haardt, German, on September 30, 1882. Hans Geiger invented a device that could detect alpha particles. (An alpha particle is a particle made up of two protons and two neutrons)
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This is what we believe the atom looks like today
