Atom History

Topics: Atom, Neutron, Proton Pages: 3 (961 words) Published: January 21, 2011
Atom History Essay
An Atom is a basic unit of matter that consists of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The Atom was theorized by a man named Democritus of Abdera, Thrace in between c.a 460 BC - ca. 370 B.C. Atom is derived from the Greek word “atomos” , which means to be uncuttable. He had a theory that everything is composed of “atoms”, which he believed that these minuscule objects are indivisible, indestructible and have and always been in motion, had a void that exists between atoms, they are solid, homogeneous, and differ in size, shape, mass, position, arrangement, etc. Democritus identified all of these qualities by using the analogies from our sense experiences. In the early 1800 John Dalton, a meteorologist/ color blindness physician, came up with his own atomic theory and The Dalton Model. Even though, the idea of atoms were already proposed by Democritus, his theory was different in that it had the weight of careful measurements behind it. John Dalton’s Atomic Theory consisted of these facts: All elements are composed of tiny indivisible particles called atoms. Atoms of the same elements are identical. The atoms of any one element are different from those of any other element. Atoms of different elements can physically mix together or can chemically combine with one another in simple whole-number ratios to form compounds Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are ever changed into atoms of another element as a result of a chemical reaction. Important changes were revised from his theory like his atoms are indivisible which is wrong since atoms can be divided into subatomic particles like Protons,Neutrons, and Electrons. Next, is his theory that Atoms of all elements are the same, this is proven wrong by the discovery of isotopes. Lastly, his theory that elements can’t be transformed into other elements, which is also proven wrong...
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