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450
Democritus and Aristotle (450 BC)
The atom was theorized when the question was asked if one continued to break down, how long would it take until one could no longer break it down? The small indivisible particle was named an atom. The theory derived from scientific observations. Huffman, Carl A. "Democritus." World Book Student. World Book, 2014. Web. 27 Feb. 2014.
"The Atom." Double Chooz Experiment | Elementary Particle Tour. Web. 26 Feb. 2014.
Harvey, Nicole M. "Atoms and the Periodic Table." Zachary High School, Lecture. -
Dalton
Dalton stated taht atoms are indestructable, indivisible particle that make up matter. He also stated atoms of the same elemet are identical and a combination of elements are compounds. Also, Dalton said chemical reactions is the rearrangement of atoms. These discoveries are called Dalton's Atomic Theory. He made these discoveries through scientific experiments. Harvey, Nicole M. "Atoms and the Periodic Table." Lecture.
"Atomic Models Webquest." Atomic Models Web Quest. Web.
27 Feb. 2014. -
Rutherford
Rutherford created a nuclear model of an atom which included a very small positively charged nuclues with a large volume surrounding it containing electrons. He also concluded that there are equal protons and electrons. Rutherford made these discoveries through an experiment known as the "Gold Foil Experiment". Harvey, Nicole M. "Atoms and the Periodic Table." Lecture.
"History of the Atom Timeline Project." History of the Atom Timeline Project Web. 27 Feb. 2014. -
Bohr
Bohr expanded Rutherford's theorized using scientific experiments in which he discovered electrons travel in fixed orbits around the nucleus and can eventually absorb energy and become "excited" and move to another orbit, but it can fall out of orbit as radiation. Bohr created a "planetary model". "A Brief History of Modern Atomic Theory." Chemistry Tutorial : History of Atomic Theory Web. 26 Feb. 2014.
"Bohr’s Atomic Model." Universe Today RSS. N.p., n.d. Web. 26 Feb. 2014. -
Heisenberg and Schrodinger
Heisenberg created the "uncertainity principle" which descirbes how it is impossibel to know of an electrons postion and speed at the same time. Heisenberg created mathematical equations to dipict the atom instead of a model. Schrodinger modified it and made the Cloud Model. "Heisenberg - Quantum Mechanics, 1925-1927: The Uncertainty Principle." Heisenberg - Quantum Mechanics, 1925-1927: The Uncertainty Principle. Web. 27 Feb. 2014.
"Timeline of the Atom." : Erwin Schrodinger. Web. 27 Feb. 2014 -
Thomson
Thomson was responsible for the discorvery of the electron. He also discovered that the elcetron is negatively charged. Through his observations, Thomson created the "Plum Pudding" Model in which the negatively charged electrons are dispersed throughout a positively charged sphere. Thomson made his discoveries through experiments. Harvey, Nicole M. "Atoms and the Periodic Table." Zachary High School, Lecture.
"Atomic Models Webquest." Atomic Models Web Quest. N.p., n.d. Web. 27 Feb. 2014.
