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Atoms
How many times can one cut a piece of gold in half? A Greek philosopher named Democritus was the first in a long line of scientists and mathematicians to try to answer this very difficult question. Around 450 BC, Democritus stated that all mater was composed of particles that he called atomos (where the English word atom comes from) and that these particles could not be cut. This went against the present day theory of Aristotle which was that matter could be cut infinitely. Unfortunately for Democritus, his theory was not accepted in his lifetime. John Dalton came up with an atomic theory of matter in 1803. In his theory he stated four theories. 1.)All mater is composed of atoms 2.) Atoms of same elements are the same 3.) Atoms of different elements are different and 4.) Atoms unite in definite whole number ratios when they form compounds. Though his theory has some errors, these theories are the basis for our understanding of atoms and chemistry. One mistake of Dalton was his belief that atoms were round and hard. This became the primary ambition for scientists after Dalton, to find out the structure of an atom. In 1897, Joseph John Thomson discovered electrons. Using a tube, magnets and charged plates, he sent ray particles through various experiments changing the position of the charged plates. By changing the plates, he discovered he could also change the point at which the particles would hit a florescent screen at the end of the tube. He decided that the ray was made up of particles with a negative charge. He named these particles electrons. ... Please login to view comments from other users.
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