History of the Atom Timeline by Joel Robinson

Aristotle (450 BC)

450

http://www.youtube.com/watch?v=NSAgLvKOPLQ&feature=youtu.be Aristotle said that all things were made of different amounts of earth, water, wind, and ether. He used ancient philosophy to come to this conclusion. He believed that all atoms were made up of earth, water, wind, and ether as well.

Democritus (450 BC)

450

http://www.youtube.com/watch?v=NSAgLvKOPLQ&feature=youtu.be Democritus began the idea of an atom. He philosiphised that if you continuously cut a piece of bread in half you will reach a point to where you can't cut the piece in half anymore. He named his discovery "atomos" which is Greek for uncuttables. He decided that everything was made of these "atomos" and they were all different shapes and sizes.

Dalton

Jan 1, 1803

http://www.youtube.com/watch?v=NSAgLvKOPLQ&feature=youtu.be John Dalton proposed the "atomic theory" with sperical solid atoms based upon measurable properties of mass. Atoms arrange in different combinations and are indivisible. He based this off of theories from observations. He developed the first truly recoognized model of the atom. Dalton created Dalton's Model of the Atom. It shows atoms as randomly arranged balls.

Thomson

Jan 1, 1897

http://www.youtube.com/watch?v=NSAgLvKOPLQ&feature=youtu.be JJ Thomson studied canal rays and found they were associated with the proton H+. To determine this he used a cathode ray tube to find change to mass ratio of an electron to equal 1.759*10^8 coloumbs/gram. He developed the plum pudding model by splitting a blueberry muffin and deciding that the bluberries were the electrons stuck in a positively charged dough.

Rutherford (1/3)

Jan 1, 1898

http://www.youtube.com/watch?v=NSAgLvKOPLQ&feature=youtu.be Rutherford studied radiations emitted from uranium & thorium and named them alpha & beta.

Rutherford (2/3)

Jan 1, 1911

http://www.youtube.com/watch?v=NSAgLvKOPLQ&feature=youtu.be Using his alpha particles as atomic bullets, he probed the atoms in a thin piece of gold foil. He established that the nucleus was very dense, small, and positively charged. He also assumed that the electrons were outside the nucleus. He developed the Nuclear Model. It showed a positve nucleus within a bigger circle containing electrons floating around in it.

Rutherford (3/3)

Jan 1, 1913

http://www.youtube.com/watch?v=NSAgLvKOPLQ&feature=youtu.be Later on he contributed to half of the Quantum Mechanical Model. He came up with the idea that the nucleus contained subatomic particles that made it positively charged. He called these subatomic particles protons (neutrons were added later by James Chadwick whom completed the Quantum Mechanical Model).

Bohr

Jan 1, 1922

http://www.youtube.com/watch?v=NSAgLvKOPLQ&feature=youtu.be Niels Bohr developed an explanation of atomic structure that underlies regularites of the periodic table. His atomic model, the Bohr Model, showed atoms built up of successive orbital shells of electrons orbiting a nucleus.

Heisenberg

Jan 1, 1927

http://atomictimeline.net/index.php Described atoms by means of formula connected to the frequencies of spectral lines. Proposed Principle of Indeterminancy which states you cannot know both the postion and velocity of a particle at the same time. He and Schrodinger's model, the Quantum Mechanical Model, shows a positive nucleus with protons and neutrons and cloud-like assortment of electrons called elctron orbitals.

Schrodinger

Jan 1, 1930

http://atomictimeline.net/ Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom. He and Heisenberg's model of the atom, the Quantum Mechanical Model, shows a positive nucleus, containing protons and neutrons, surrounded by a cloud-like orbital of electrons.

bibliography

Feb 27, 2014

"Models of the Atom Timeline." YouTube. YouTube, 06 Dec. 2012. Web. 27 Feb. 2014. "Atomic Structure Timeline." Atomic Structure Timeline. N.p., n.d. Web. 26 Feb. 2014.