-
450
Aristotle (350 B.C.)
Aristotle taught that there were no atoms. He thought that everything was made of fire, water, air, and earth. This thoery was from observation and he did not have a model because he did not believe that atoms exsisted. -
450
Democritus (450 B.C.)
In 450 BC Democritus thoerized that the world consists of an infinite amount of atoms that move in an infinite void. They can't be seen or destroyed. They differ from one another in size, shape, color, and position. Each world is a different combination of atoms and there are inumerable other worlds because their are an infinte number of atoms. Atoms are always moving. Democritus made this theory from observation and he thought that the model of the atom was just a round sphere with no p+,e,or n -
Dalton
Dalton believed that elements were made of atoms and that elements are pure substances. Also, that all of the atoms of an element have the same mass. And that a compound is elements are bonded together and have a fixed ratio of elements. Akso chemical reactions involve a rearrangement of combinations of atoms. Dalton got his theory from research and observation and his model is called Dalton's model. -
Thompson
Thompson discovered the electron. He believed that the rings around the atom were tiny pieces of matter. To make his discovery he built a cathode-ray tube in which rays passed through a vacuum in a glass tube. The rays seemed to come from cathode (negatively charged) so he knew they were negatively charged. He thought the atom had electrons around the
nucleus.He called his model the "Plum Pudding Model". -
Period: to
Atom Timeline
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Rutherford
Rutherford was the first scientist to break up the nucleus of an atom. He noticed that there were different pieces to a nucleus, and also that there is a lot of empty space between the nucleus and its electrons. Rutherford's most famous experiment was the Gold Foil experiment, which is what developed his theory, and also revealed that the atom has a positive nucleus and is surrounded by negative electrons, and that most of the mass of the atom is located in the nucleus. -
Bohr
Bohr was the scientest to discover a bit more information about the electrons in an atom. He found that electrons orbit the nucleus, and the energy of an electron is proportional to the distance from the nucleus ( more distance = more energy ). Bohr also noted that light is absorbed when an electron jumps to a higher orbit and light is emitted when an electron jumps to a lower orbit. Bohr made a model for his theory, and made his theories from observation. -
Heisenberg
Heisenberg was a scientist to also discover much about the electrons. He found that a particle's position, momentum, or energy can never be precisely determind. This principle exists because measuring any variable disturbs the others in an unpredictable way. This is called the uncertainty principle. Heisenberg got his theory from observation. -
Schrodinger
Schrodinger was Heisenberg's partner and also helped with some of his discoveries. Schrodinger made a model in which it shows electrons as waves, and also tries to show the region in which electrons reside. Instead of showing where the electron is, Schrodinger's model describes the probability that an electron will be in a given region at a given time. The model does not show where the electrons are, just where they might be. He obtained his theory from his model and observation. -
Bibliographies P.2
"Physics 2000." Physics 2000. N.P., n.d. Web. 27 Feb. 2014.
http://www.colorad.edu/physics/2000/index.pl -
Bibliographies
"Atom History." Atom History. N.p., n.d. Web. 27 Fed. 2014.
http://molaire1.perso.sfr.fe/e_histoire.html.
"Atomic Models." Atomic Models. N.p., n.d. Web. 27 Feb. 2014.
http://cronodon.com/Atomic/AtomTech2.html
"Atomic Structure Timeline." Atomic Structure Timeline. N.p., n.d.
Web. 25 Feb. 2013. http://atomictimeline.net/index.php.
"Google Images." Google Images. N.p., n.d. Web. 26 Fedb. 2014.
http://images.google.com/.
