-
450
Aristotle (360 B.C.)
- he thought matter must be made of smaller pieces because things can be continuosly broken down. --he gathered scientific facts which proved his work. -believed atoms were a smallest part of matter. "Chemistry Project : The History Of The Atom." Chemistry Project : The History Of The Atom. Britannica, n.d. Web. 26 Feb. 2014. Harvey, Nicole C. "Aristotle." Concept 2. Louisiana, Zachary. 27 Feb. 2014. Reading.
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450
Democritus Continued
"Chemistry Project : The History Of The Atom." Chemistry Project : The History Of The Atom. Britannica, n.d. Web. 26 Feb. 2014. -
450
Democritus (460 B.C.)
-developed the idea of atoms
-argued there is a smallest bit of matter, the world has a infinite number of them, they are invisible, and are each different.
-he made his discovery from observations of matter and the void (space).
-thought the atom's solidness corresponded with the material that made it.
-the Democritean atom is an inert solid that interacts with other atoms mechanically.
Walker, Jim. "History of Atoms." History of Atoms. E-Prime, 2004. Web. 23 Feb. 2014 -
Dalton
-he said all atoms are indivisible, indestructible, can form a chemical reaction (rearrangment), form compounds(two or more different atoms), & atoms in elements are identical.
-he performed experiments and observed lumpy matter (atoms).
-believed atoms were ball-like and in different combos =compounds. HISTORY OF THE ATOM FROM DEMOCRITUS TO BOHR AND SCHRÖDINGER." HISTORY OF THE ATOM FROM DEMOCRITUS TO BOHR AND SCHRÖDINGER. 25 Feb. 2014.
Walker, Jim. "History of Atoms." Nov. 2004. Web. 23 Feb. -
Thomson
-he discovered electron
-realized an atom has: smaller pieces (protons and electrons) and positive and negative charges are = in magnitude since a atom is neutral.
-used cathode ray tubes.
-thought atom was a sphere of positive charge with embedded negative electrons. "The Plum Pudding" Atomic Structure Timeline." Atomic Structure Timeline. N.p., 2004. Web. 25 Feb. 2014.
"HISTORY OF THE ATOM FROM DEMOCRITUS TO BOHR AND SCHRÖDINGER." HISTORY OF THE ATOM FROM DEMOCRITUS TO BOHR AND SCHRÖDINGER. -
Rutherford
-discovered large atomic nucleus and attraction of electrons around it.
-nucelus has a positive charge and majority of atomic mass.
- gathered evidence by conducting the Gold Foil Experiment
-he had the Atomic Planetary Model with the nucleus in the center and the electrons surrounding it. Atom History." Atom History. N.p., 2011. Web. 27 Feb. 2014.
Harvey, Nicole C. "Rutherford." Concept 2. Louisiana, Zachary. 27 Feb. 2014. Reading. -
Bohr Continued
Harvey, Nicole C. "Bohr." Concept 2. Louisiana, Zachary. 27 Feb. 2014. Reading. Walker, Jim. "History of Atoms." History of Atoms. E-Prime, Nov. 2004. Web. 23 Feb. 2014. -
Bohr
-discovered protons in nucleus and electrons surrounded it, electrons are in only certain energy levels, outer electron determine the chemical property, and electrons with low energy orbit closer to nucleus.
-he observed the emission spectra of hydrogen
-created the Bohr Model A Brief History of Modern Atomic Theory." Chemistry Tutorial : History of Atomic Theory. n.d. Web. 25 Atom History." Atom History. N.p., 2011. Web. 27 Feb. 2014. -
Heisenberg and Schrodinger Continued
Harvey, Nicole C. "Structure of an Atom-Model." Concept 2. Louisiana, Zachary. 27 Feb. 2014. Reading. HISTORY OF THE ATOM FROM DEMOCRITUS TO BOHR AND SCHRÖDINGER." HISTORY OF THE ATOM FROM DEMOCRITUS TO BOHR AND SCHRÖDINGER. N.p. Web. 25 Feb. 2014. -
Heisenberg and Schrodinger
-Schrodinger discovered that electrons are located on orbitals which are basically electron density clouds. He did this by creating equations/wave functions for electrons.
-Heisenberg created the uncertainty principle which means it is not possible to locate and know the speed of an electron simultaneously. He used Broglie's hypothesis for this.
Schrodinger and Heisenberg both contributed to the model of the atom used today.
