History of the Atom Timeline

Aristotle

400

Aristotle believed that all matter was made of the Four Elements: Fire, Earth, Air, and Water- theory https://www.gaggle.net/gaggleVideoProxy.do?op=view&v=56f60323e745304a6deba9eeba2c9245

Democrotus

460

Democritus believed that if you break down an objects enough times, eventually you wouldn't be able to break it down any smaller, and that piece is called an atom- theory https://www.gaggle.net/gaggleVideoProxy.do?op=view&v=56f60323e745304a6deba9eeba2c9245

Dalton

Jan 1, 1808

Dalton believed that different atoms bonded to create different things and that they were indivisible- theory
Thompson also created a mass spectrograph which found isotopes. https://www.gaggle.net/gaggleVideoProxy.do?op=view&v=56f60323e745304a6deba9eeba2c9245 http://www.universetoday.com/38169/john-daltons-atomic-model/

Thomson

Jan 1, 1904

Thomson believed that atoms were made of electron; he changed the previous model by saying atoms were not indivisible- theory https://www.gaggle.net/gaggleVideoProxy.do?op=view&v=56f60323e745304a6deba9eeba2c9245

Rutherford

Jan 1, 1911

Rutherford discovered that stoms had a nucleus with all positive charge was in the center; he changed the previous model by saying atoms had a nucleus.
He gathered evidence by using the gold foil expirement. https://www.gaggle.net/gaggleVideoProxy.do?op=view&v=56f60323e745304a6deba9eeba2c9245

Bohr

Jan 1, 1913

He discovered that electrons orbit around the nucleus.
He changed the previous model by saying electrons orbited in a circular motion around the nucleus. https://www.gaggle.net/gaggleVideoProxy.do?op=view&v=56f60323e745304a6deba9eeba2c9245

Heiseburg and Schrodinger

Jan 1, 1920

The discovered that electrons move around the nucleus quickly in a sphere. He made the previous atom more accurate by adding properties such as velocity and position. He came up with the electron cloud. https://www.gaggle.net/gaggleVideoProxy.do?op=view&v=56f60323e745304a6deba9eeba2c9245