Chem Timeline

The Timeline for Atomic Model

Rutherford Atomic Model

Electron Cloud Model

Thompson Atomic Model

Dalton's Atomic Model

Bohr Atomic Model

Democritus Atomic Model

Electron cloud model

Thompson's drawing

Ernest Ruthford conducted an experiment to test the atomic structure of matter.He fired Alpha particles at a piece of gold and found that an atom was full of space.

Neils Bohr described the atom as having electrons orbit the nucleus in orbits that have a set size and energy.

John Dalton,in his study of meteorology, used Democritus theory to formulate more components of an atom.

Democritus was a student of Leucippus, They both developed the atomic theory while trying to overthrow Parmenides' theory.

Erwin Schrodinger developed a mathematical function that determined the energy and electron can have and the probability of finding the electron in various places around the nucleus.

J.J. Thomson discovered the electron, the first subatomic particle. He also was the first to attempt to incorporate the electron into a structure for the atom.

Bohr's Model

The Bohr model also show how he energy of the orbit is related to its size and how electrons move from different orbits

He then concluded that the weigh of an atom is concentrated at a central core called the nucleus and that the electrons were moving around it in an orbit.

Rutherford's Model

Atomic orbitals

Democritus described atoms as being indestructible and containing no empty space.

Dalton's Model

Democritus Model

As Dalton experimented with various gases he deduced that atoms of an element cannot be created, destroyed, broken into smaller parts or transformed into atoms of another element.

What Thompson imagined

The function uses points to show where the electron is mostly to be. All of the points form a "Cloud" around the nucleus. That is why is is called the electron cloud model.

Thompson described the atom as being a spherical entity containing electrons confined in a homogenous jelly.

Rutherford's model shows that the atom was like a miniature solar system: the electrons circled the nucleus in wide orbits just as planets orbit the sun.

The Bohr Model is a planetary model in which the negative electrons orbit a small, positively-charged nucleus similar to the planets orbiting the Sun

Although his atomic theory went into detail the model stayed the same.

His atomic model consisted only of a solid sphere but he describe the atom as being able to take on many different shapes

The Thomson Model has electrons and a sphere of positive charge. There are no protons in the Thomson Model of the atoms.

Due to the Heisenberg uncertainty principle, there is no fixed electron orbit around the nucleus. The electron model aloud scientists to construct atomic orbitals to show the areas of high probability for finding the electron.

1911

1913

1803

1897

1925

400 BC

Significant People

Parts of an Atom

Electron

Hantaro Nagaoka

Louis de Broglie

J.J. Thompson is credited with the discovery of electrons in 1897. After experimenting with cathode rays, he proposed that atoms were made up of particle. He named the particles corpuscles, which we now call electrons.

Louis de Broglie ,in 1923,proposed that electron share some of the same properties as waves. Later, this was confirmed and is now called a wave-particle duality.

Hantaro Nagaoka, in 1904, suggested that the atom had a nucleus in the center and that the electrons revolved around it in a planetary fashion.

Protons

Neutron

Robert Millikan

Eugen Goldstein

Although Edwin Schodinger proposed it, James Chadwick in 1932 confirmed the existence of neutrons. He used a complicated mathematical computation to detect a neutral particle bigger than an electron. He then deduce it was a different kind of particle and called it an neutron.

The Proton was discovered by Ernest Rutherford in 1911. He proposed that if positive atoms existed, that there had to be something with a positive charge inside the atoms to give them there charge. After experimenting with helium, he discovered protons.

Robert Millikan, in 1909, developed the oil-drop experiment. It successfully detected and measured the effect of an electron.

Eugen Golstein ,in 1886, discovered the positively-charged particles formed when electrons are removed from the gas particles in a cathode-ray tube. He called them anode rays,which laid precedence to the discovery of the proton.

Works Cited

"Atomic Theory." Robot Platform. N.p., 2010. Web. Sept.-Oct. 2012. <http://www.robotplatform.com/knowledge/Atomic%20Theory/atomic_theory.html>.

"Electron Cloud Model." Tangent LLC. N.p., 25 Apr. 2007. Web. Sept.-Oct. 2012. <http://lionsgensci.wikispaces.com/Electron+Cloud+Model+(Louis+de+Broglie+%26+Erwin+Schrodinge)>.

"Eugen Goldstein." NNDB. Soylent Communications, 2010. Web. 04 Oct. 2012. <http://www.nndb.com/people/887/000169380/>.

Helmenstine, Anne M., Dr. "Bohr Model of the Atom." About.com Chemistry. About.com, n.d. Web. 04 Oct. 2012. <http://chemistry.about.com/od/atomicstructure/a/bohr-model.htm>.

Jessa, Tega. "John Dalton's Atomic Model." Universe Today. N.p., July-Aug. 2009. Web. 04 Oct. 2012. <http://www.universetoday.com/38169/john-daltons-atomic-model/>.

Knierim, Thomas. "The Atomistic Philosophy of Leucippus and Democritus." TheBigView. N.p., July-Aug. 2012. Web. 04 Oct. 2012. <http://www.thebigview.com/greeks/democritus.html>.

Leon, N. "Rutherford Model of the Atom." Chemistry 101 Class Notes. N.p., 5 Jan. 2001. Web. 04 Oct. 2012. <http://www.iun.edu/~cpanhd/C101webnotes/modern-atomic-theory/rutherford-model.html>.

Rubin, Julian. "Robert Millikan The Oil-Drop Experiment." Following the Path of Discovery. N.p., July-Aug. 2012. Web. 04 Oct. 2012. <http://www.juliantrubin.com/bigten/millikanoildrop.html>.

"Rutherford's Experiment and Atomic Model." Encyclopedia of Science. N.p., n.d. Web. 04 Oct. 2012. <http://www.daviddarling.info/encyclopedia/R/Rutherfords_experiment_and_atomic_model.html>.

Senese, Fred. "Dalton's Atomic Theory." General Chemistry Online. N.p., June-July 2005. Web. 04 Oct. 2012. <http://antoine.frostburg.edu/chem/senese/101/atoms/dalton.shtml>.

Siegel, Ethen. "Science Blogs." Starts With A Bang. N.p., Sept.-Oct. 2010. Web. 04 Oct. 2012. <http://scienceblogs.com/startswithabang/2010/10/05/the-story-of-the-neutrino/>.

Stanley, Kent. "A Look Inside the Atom." The Discovery of the Electron. American Institute of Physics, Oct.-Nov. 2002. Web. 04 Oct. 2012. <http://www.aip.org/history/electron/jjhome.htm>.

Takada, Kenjiro, Dr. "Thomson Model." Microscopic World -1- Mysteries in the Atomic World. N.p., 15 May 2005. Web. 04 Oct. 2012. <http://www.kutl.kyushu-u.ac.jp/seminar/MicroWorld1_E/Part2_E/P24_E/Thomson_model_E.htm>.

"Thomson Model of the Atom." ChemTeam. N.p., Aug.-Sept. 2001. Web. 04 Oct. 2012. <http://www.chemteam.info/AtomicStructure/Thomson-Model-Intro.html>.

Villanueva, John. "Electron Cloud Model." Universe Today. N.p., July-Aug. 2009. Web. 04 Oct. 2012. <http://www.universetoday.com/38282/electron-cloud-model/>.

Whehell, William. "Protons." History of Science. N.p., 20 Jan. 2007. Web. 04 Oct. 2012. <http://historyofsciences.blogspot.com/2007/01/protons.html>.

Wilbraham, Antony, Michael Matta, and Edward Waterman. "Electrons in Atoms." Chemistry. Ed. Dennis Staley. Boston: Prentice-Hall, 2005. N. pag. Print.