Fall.2008.MMA.Golder.Geoffroy.Timline

Leucippus and Democritus (left) Born- unknown, 460 BC (respectively) Died- unknown 370 BC (respectively) Leucippus and Democritus were Greek philosophers who, pioneered the theory of atomism. This theory was first developed by Leucippus who was the originator of the idea that everything was comprised of minute, uniform, indivisible particles called atoms (literally a-no, tom-cut; a-tom = no cut). Unfortunately, not much is known about Leucippus as his work was greatly overshadowed by his pupil Democritus. Democritus, however, took that idea and developed it into a theory that which could be practically applied to explain the real world. Democritus' key points are: -3 Properties of atoms: size, shape, weight - Interactions of atoms produce all other properties of matter we sense - The state of matter we sense is result of the properties of the atom

www.thebigview.com/greeks/**democritus**.html http://www.sparknotes.com/philosophy/presocratics/section10.rhtml

**John Dalton-** Born- 6 September 1766 Died- 27 July 1844 What he did- Wrote 4 essays called "Experimental Essays" which introduced mixed gases, pressure of steam and other vapors at different temperatures, evaporation and thermal expansion. 5 main points to his theory:
 * English Chemist, meteorologist and physicist

1.Elements are made of tiny particles called atoms 2.All atoms of a given element are identical 3. No atom is the same 4. Atoms of one element can combine with atoms of other elements to form chemical compounds 5. Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process

http://scienceworld.wolfram.com/biography/Dalton.html http://www.bookrags.com/biography/john-dalton/ 



Born:1754 Died:1826 Proust's largest contributions to chemistry is the law of definite proportions. The law of definite proportions states that a chemical compound has the same number of proportions by mass. To do this experiment, Proust made artificial copper and compared it to real copper. He concluded that both the coppers contained the same portion of Copper, Carbon, and Oxygen. while living in Spain, he worked for the Spanish government, doing geological surveys and analyzing the nation's mineral resources. This led him to discover that sucrose came from grapes.
 * [[image:proust.jpg align="left"]]Joseph Proust-**(Published paper in 1794)
 * French chemist

http://www.bookrags.com/biography/joseph-louis-proust-wsd/ http://www.answers.com/topic/joseph-proust  

Born: October 10, 1734 Died: February 24 1810 Henry Cavendish was a British scientist whose entire professional life was spent doing research on the various components of air. His greatest claim to fame was his discovery of Hydrogen although, equally important, was that he was able to accurately break down air into its various components and measure them. This work was also notable because he was the first scientist to collect evidence of and eventually prove the elemental nature of hydrogen. His life was marked by an intense shyness and outside his family he formed no meaningful personal relationships. Cavendish's shyness may explain why his work on other ares of science was not published until other scientists found them or had taken credit for his discoveries.
 * Henry Cavendish**

www.chemistry.mtu.edu/~pcharles/SCIHISTORY/**HenryCavendish**.html

Born: February 8, 1834 Died: February 2, 1907 Dimitri Mendeleev was born into an upper middle class family near Tobolsk, Russia in 1834. After attending various schools, in his home town and in St Petersburg he became a teacher at Simferopol Gymnasium No. 1. From this position his career took off and he eventually became a Doctor of Science and brought the Saint Petersburg Technological Institute to the forefront of chemistry research. During his time at SPIT he began to research periodic trends and developing his ideas for what would become the periodic table. Mendeleev's periodic table was published in 1869, although he was not the first to publish work on arranging the elements his table was the first to enable scientists to predict new elements. On a worthy side note Mendeleev was placed in charge of developing state standards for vodka production in 1893, he discovered that the ideal vodka would, chemically speaking, have 38% alcohol by volume however due to tax reasons the state sold it as 40% by volume.
 * Dmitri Mendeleev** (published periodic table in 1869)

www.chemistry.co.nz/**mendeleev**.htm

Born:1845 Died:1923 Roentgen received the first Nobel prize in physics for his x-ray discovery in 1895. He was repeating a cathode ray tube experiment done by Philipp von Lenard when he observed florescence on a piece of cardboard coated with barium platinocyinade. This observation prompted him to begin a new series of experiments with the goal if determining the cause of this florescence and if it were unique to the Lenard tube he used to conduct the original experiment. When he darkened the room to test the opacity of the cover he made for the tube, he observed the florescence again even though the cardboard was around a meter from the tube. These observations led him to the conclusion that there was another kind of ray being transmitted by the tube. After this he began research ways to stop the rays and when he introduced a piece of lead to the rays he produced the first X-Ray image of himself.
 * [[image:roentgen-1-medium.gif align="left"]]Wilhelm C Roentgen**-(Nobel prize 1901)
 * German Physicist

http://www.makingthemodernworld.org.uk/people/BG.0193/ http://www.akisrx.com/inglese/htm/roentgen.htm

**Marie Curie**-(Nobel prize 1903) Born:1867 Died:1934 She is the only person to be awarded the Nobel prize in two different sciences.She named **polonium,** the first new chemical element she discovered, for her native country Poland. She also did pioneering research in the field of radiation and gave the name "radioactivity" to the emission of radiation from atoms. She proved that this was due to internal atomic decay and was not the result of an interaction between different atoms or molecules. With her husband, they refined eight tons of raw ore to produce one gram of radium, the second element she discovered. Her father also taught math and physics, subjects that Maria would become very known for in her later years when she earned a Nobel prize in physics. She eventually died complications from her many exposures to radiation throughout the course of her work.
 * Polish physicist and chemist

http://nobelprize.org/nobel_prizes/physics/laureates/1903/marie-curie-bio.html http://books.google.com/books?hl=en&id=MJNOf9WvFxwC&dq=Marie+Curie-&printsec =frontcover&source= web&ots=A_6Mq7E0FS&sig=A7RSj2_0BQi1g1at9UvnYQzijyQ&sa=X&oi=book_result&resnum=8&ct=result#PPA11,M1 

Born: 1852 Died: 1908 In 1903, Becquerel, a French physicist, was awarded a Nobel prize in physics for taking part in the discovery in radioactivity by accidentally discovering radiation while conducting experiments on uranium salts. In these experiments Becquerel wrapped florescent uranium salts in photographic plates and before he could expose them to sunlight he found them already fully exposed. This demonstrated that uranium emitted its own radioactive rays, radiation. Becquerel showed that the rays emitted by uranium, caused the plates to ionize and that they differed from x-rays in that they could be deflected by electric or magnetic fields. Becquerel published his findings in many papers, two of which are the Annales de Physique and Comptes Rendus de l'Academie des Sciences.    http://nobelprize.org/nobel_prizes/physics/laureates/1903/becquerel-bio.html http://www.physics.isu.edu/radinf/cuire.htm
 * [[image:henri_b.jpg align="left"]]Henri Becquerel**-(Nobel prize 1903)

**J.J Thomson-**(Nobel prize 1906) Born:1856 Died:1940 A British physicist who experimented with sending currents of electricity through glass tubes. He concluded that the mysterious rays created are streams of particles much smaller than atoms, that they are in fact minuscule pieces of atoms. In his second experiment, he tried to see whether or not rays of light could be deflected by an electric field. He found out that the rays could be bent by the electrical field passed through the light. After performing his third experiment, he created his plum pudding model. This model was his imagination of all the positive ions that made up an atom.
 * British Physicist

http://nobelprize.org/nobel_prizes/physics/laureates/1906/thomson-bio.html http://www.aip.org/history/electron/jjhome.htm

In 1903, J.J. Thompson formed a model that shows an atom and the positive and negative charges surrounding it. The electrons were thought to be positioned throughout the atom, but with many structures possible for positioning multiple electrons, particularly rotating rings of electrons. This model was rejected when Rutherford performed the alpha particle scattering experiment and put forth his model of the atom. http://library.thinkquest.org/28582/history/plum.htm www.bookrags.com/wiki/**Plum**_**pudding**_**model** 
 * [[image:plum_pudding.gif width="189" height="189" align="left"]]Plum Pudding model-**

Born: August 30, 1871 Died: October 19, 1937 Did an experiment in which he shot alpha particles at a very thin piece of gold foil and measured their deflection but was baffled by the results, as he observed several particles bouncing back at source. He created a model to explain his results, then wrote the Nuclear theory of the atom. These results led him to the conclusion that the current plum pudding model of the atom was incorrect and began to speculate as to other possible structures of the atom. In 1907, at the University of Manchester, he demonstrated the nuclear nature of atoms. It was his interpretation of this experiment that led him to the Rutherford model of the atom, with a very small positively charged neutrons surrounded by electrons.
 * Ernest Rutherford**- (Nobel prize 1908)
 * New Zealand Physicist

nobelprize.org/nobel_prizes/chemistry/laureates/1908/**rutherford**-bio.html www.chemheritage.org/classroom/chemach/atomic/**rutherford**.html

The Planetary model is also known as the Rutherford model. The Rutherford model was basically put together by Rutherford to prove that J.J Thompson's plum pudding model was incorrect. Rutherford’s model was also called the planetary model because it resembled the solar system in a few ways. His model had a nucleus, and electrons circling around it, similar to the sun and the planets. The Rutherford model did not attribute any structure to the orbits of the electrons themselves.
 * [[image:planet.jpg width="204" height="153" align="left"]]Planetary model-**

[|http://www.iun.edu/~cpanhd/C101webnotes/modern-atomic-theory/rutherford-model.html] http://www.vias.org/physics/bk4_03_01b.html

Born:1885 Died:1962 Bohr was a native of Denmark, and he did all his work and studies there too. After receiving his doctrine, he went to England where he began to work on the problems with the atoms structure. He found a few things wrong with Rutherford's Cloud model and proposed to add the model of quantum by Max Planck. This created great evidence that the theories put forth by other physicist in the past were to be true. He was only 37 when he received the Nobel prize for his work, so he continued to study the atom. He also presented his idea of a liquid nucleus.
 * [[image:bohr.jpg width="177" height="252" align="left"]]Niels Bohr**-(Nobel prize 1922)
 * Danish physicist

__nobelprize.org/nobel_prizes/physics/laureates/1922/**bohr**-bio.html__ __http://www.lucidcafe.com/library/95oct/nbohr.html____ http://www.pbs.org/wgbh/aso/databank/entries/bpbohr.html__

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Born:1868 Died:1953 Millikan's work formed some of the basis ideas for modern particle physics. While a professor at the University of Chicago, two physicists Millikan and Harvey Fletcher measured a single charge on an ion by using an oil drop experiment. For this, only Millikan received a Nobel prize for Fletcher was to not take credit for any of it in exchange for something else. The experiment had a big effect on the accuracy of information on the fundamental unit of charge and provided proof that a charge is quantized.
 * [[image:millikan.jpg width="179" height="222" align="left"]]Robert Millikan-**(Nobel prize 1923)
 * American Physicist

nobelprize.org/nobel_prizes/physics/laureates/1923/**millikan**-bio.html scienceworld.wolfram.com/biography/**Millikan**.html  <span style="font-size: 12pt; line-height: 150%; font-family: 'Arial','sans-serif'"> <span style="font-size: 12pt; line-height: 150%; font-family: 'Arial','sans-serif'">

<span style="font-size: 12pt; line-height: 150%; font-family: 'Arial','sans-serif'"> <span style="font-size: 12pt; line-height: 150%; font-family: 'Arial','sans-serif'"> **Werner Heisenberg-**(1925) Born: 1901 Died: 1976 Due to allergies, Heisenberg seasonally lived on the Island of Heligoland where he worked with the atomic model. He began to apply mathematical problems into atomic physics, this was called Matrix Mechanics. In 1925 Heisenberg formulated the matrix mechanics representation of quantum mechanics. He wrote his first paper on quantum mechanics in 1925 and 2 years later stated his uncertainty principle. His work used matrix methods made possible by Cayley on matrices 50 years earlier.This was the most productive time of his career, soon the Nazis would play a role in his researching. He was assigned to a nuclear bomb group of scientists by the Nazis, but was later jailed due to it. After 6 months of prison, He re-opened the Kaiser Wilhelm Institute for Physics.
 * German theoretical physicist

nobelprize.org/nobel_prizes/physics/laureates/1932/**heisenberg**-bio.html

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<span style="font-size: 12pt; line-height: 115%; font-family: 'Arial','sans-serif'">Born:1887 <span style="font-size: 12pt; line-height: 115%; font-family: 'Arial','sans-serif'"> <span style="font-size: 12pt; line-height: 115%; font-family: 'Arial','sans-serif'">Died:1961 <span style="font-size: 12pt; line-height: 115%; font-family: 'Arial','sans-serif'"> <span style="font-size: 12pt; line-height: 115%; font-family: 'Arial','sans-serif'">Schroedinger was an Austrian physicist who is known for his theories and ideas in quantum mechanics. He proposed his own theories such as the Schroedinger cat thought and the Schroedinger equation. The Schroedinger equation states how a quantum state of a physical system changes over time. Solutions to the equation describe atomic and subatomic systems, electrons and atoms. His cat thought theory illustrates what he saw as the problem of the Copenhagen of quantum mechanics being applied to everyday objects. The thought experiment presents a cat that might be alive or dead. Schrodinger presented four papers, the first one in 1926 being the most significant to physics and chemistry. His first paper that was presented was on wave lengths which is also known as his Schroedinger equation. His second paper solved the quantum harmonic oscillator. It also made a slight change in his Schroedinger equation. His third and fourth papers were of less significance to his career and quantum mechanics and are the last of his series of papers. <span style="font-size: 12pt; line-height: 115%; font-family: 'Arial','sans-serif'">
 * [[image:portrait-schrodinger.jpg width="196" height="264" align="left"]]Erwin Schroedinger-** (Nobel Prize 1933)
 * Austrian physicis <span style="font-size: 12pt; line-height: 115%; font-family: 'Arial','sans-serif'"> <span style="font-size: 12pt; line-height: 115%; font-family: 'Arial','sans-serif'">t <span style="font-size: 12pt; line-height: 115%; font-family: 'Arial','sans-serif'">

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 * [[image:electron_cloud_model.jpg width="298" height="316" align="left"]]

Electron cloud model**- Developed by Erwin Schroedinger, the electron cloud model demonstrates where in an atom you would most likely find electrons around the nucleus. How an electron cloud model works is the cloud will be denser in the area where there is a less probability of finding electrons.

http://regentsprep.org/Regents/physics/phys05/catomodel/cloud.htm en.wikipedia.org/wiki/**Electron**_**cloud**

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Born:1891 Died:1974 Chadwick attended the Universities of Manchester an Cambridge. After college he went to work at a University of Berlin at the start of WWI. He was a prisoner of war for four years. After WWI he was sent back to England where he set up his laboratories and continued his work at Cambridge University. In 1932 Chadwick had discovered the part of an atom located inside the nucleus called the neutron. He continued the studies that were done by Rutherford and was able to prove that a neutron had a .1% bigger mass than the proton. His new idea changed the picture and idea of the atom and accelerated the discoveries in atomic physics.
 * [[image:james-chadwick-1-sized.jpg align="left"]]James Chadwick**-(Nobel prize 1935)
 * English physicist

nobelprize.org/nobel_prizes/physics/laureates/1935/**chadwick**-bio.html http://www.thocp.net/biographies/chadwick_james.htm

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Created by Ernest Rutherford, this model corrected that of J.J Thompson and included a few more features that modeled an atom. The model contained a higher charge in the center focusing around the nucleus, which also included most of the mass of the atom. It also had smaller electrons orbiting around the nucleus. These electrons that are focused in the center of an atom help deflect alpha and beta particles. The Rutherford model did not attribute any structure to the orbits of the electrons themselves. Rutherford's model helped lead to many things in modern science such as the discovery that the atom is actually made up of subatomic particles rather than just one. It also led Rutherford to his gold foil experiment.
 * [[image:rutherford_atomic.jpg align="left"]]Rutherford-Bohr model-**(1913)

en.wikipedia.org/wiki/Rutherford_**model**