Fall.2008.MMA.Dickinson.Timeline

By Samantha Foley and Brendan Dickinson
 * __The History of the Atom__**


 * __450 AD and Years Prior__**

Born sometime in the 5th century
 * Leucippus**



Leucippus was born in Emlea, Abdera or Miletus. Leucippus is named as the originator of the theory that the universe has two different elements, which Leucippus called ‘the full’ or ‘solid,’ and ‘the empty’ or ‘void. The contribution to the developed atomist theory is unavailable. The reports refer to the views of Democritus alone, or to both atomists together; Epicurus seems to have denied that Leucippus even ever existed.

http://plato.stanford.edu/entries/leucippus/ http://www.aetheoraem.com/Leucippus1.jpg http://www.mlahanas.de/Greeks/LX/LeucippusWorld.jpg

460-370 BCE. -Born at Abdera, Greece (Nestos River.)
 * Democritus**



Democritus was a significant ancient greek scientist and philosopher. He made major contributions to the evolution of the atom. It was Democritus's Atomic Theory of the Universe that said atoms can not be destroyed, that they exist in a void, and they differ only in shape, position and arraigement. The tiny invisible particles he called atoms. Leucippus was the first ancient greek to first introduce the concept of the atom. Leucippus stated that atoms were the basis of all matter and Democritus expanded on that statement. Democritis and his teacher did not support this theory and developed the idea of the atom. Democritus is the more famous scientist of of the two. Most of this writings have not survived history but what he says was passed down. He claimed that atoms are the reason we percieve objects as we do. They create shape and form of all matter.

http://faculty.washington.edu/smcohen/320/Democritus.jpg http://plato.stanford.edu/entries/leucippus/

384BC-322BC
 * Aristotle**

Aristotle was born in 384 BCE. at Stagirus, a Greek colony and seaport on the coast of Thrace. Aristotle declares the existence of only four elements: fire, air, water and earth. All matter is made up of these four elements and matter had four properties: hot, cold, dry and wet.

[|http://www.columbia.edu/itc/chemistry/chem-c2507/navbar/chemhist.] http://www.ilt.columbia.edu/Publications/Projects/digitexts/aristotle/aristotle.jpg


 * __1700-1800__**

1766–1844
 * John Dalton**

John Dalton was born in a Quaker family in Cumberland, England, and was a teacher and public lecturer, beginning at the age of 12. Dalton arrived at his view of atomism by way of meteorology, in which he was seriously interested for a long time. He kept daily weather records from 1787 until his death. He proceeded to calculate atomic weights from percentage compositions of compounds, using an arbitrary system to determine the likely atomic structure of each compound.

http://www.chemheritage.org/classroom/chemach/periodic/dalton.html http://upload.wikimedia.org/wikipedia/commons/e/e9/John_Dalton.jpg

1733–1804
 * Joseph Priestley**

Priestley was educated to be a minister in the churches and he spent most of his life professional time as a teacher. He questionned the divinity of Jesus, while accepting Christianity and ironically became an early Unitarian. He was best remembered for his dis covery of oxygen and was welcomed to the United States. He was at least as well for his prodigious political and theological writings as for his scientific contributions. Priestley's first scientific work, "The History of Electricity", was encouraged by Benjamin Franklin, whom he had met in London. In preparing the publication Priestley began to perform experiments—at first to reproduce those reported in the literature but later to answer questions of his own. In the 1770s he began his most famous scientific research on the nature and properties of gases. At that time he was living next to a brewery, which provided him with carbon dioxide.

http://www.chemheritage.org/classroom/chemach/forerunners/priestley.html http://cepa.newschool.edu/het/profiles/image/priestley.jpg

1743–1794
 * Antoine Laurent Lavoisier**

Lavoisier completed a law degree because of family wishes. His real interest, however, was in science. His earliest scientific work in geology, he was elected in 1768, at the age of 25, to the Academy of Sciences, France's most elite scientific society. In 1775 Lavoisier was appointed a commissioner of the Royal Gunpowder and Saltpeter Administration and took up residence in the Paris Arsenal. He equipped a fine laboratory, which attracted young chemists from all over Europe to learn about the "Chemical Revolution" then in progress. He meanwhile succeeded in producing more and better gunpowder by increasing the supply and ensuring the purity of the constituents saltpeter (potassium nitrate), sulfur, and charcoal, as well as by improving the methods of granulating the powder.

http://www.chemheritage.org/classroom/chemach/forerunners/lavoisier.html http://content.answers.com/main/content/img/scitech/HSantoin.jpg


 * __1800-1875__

Niels Bohr** 1885-1962

Bohr attended the University of Copenhagen, winning a gold medal from the Royal Danish Academy of Sciences and Letters for his theoretical analysis of precise experiments on the vibrations of water jets as a way of finding surface tension. Bohr moved to Manchester where he worked on the theoretical implications of the nuclear model of the atom recently proposed by Rutherford and known as the Rutherford atomic model. He recognized that the various physical and chemical properties of the elements depend on the electrons moving around the nuclei of their atoms and that only the atomic weight and possible radioactive behaviour are determined by the small but massive nucleus itself. http://www.crystalinks.com/bohr.html http://upload.wikimedia.org/wikipedia/commons/5/5e/Niels_Bohr_Date_Unverified_LOC.jpg

**William Crookes** 1833-1919  Crookes first important discovery was made in 1861 when he discovered the element thallium, with the help of spectroscopy. Crookes radiometer, in which a system of vanes, each blackened on one side and polished on the other, is set in rotation when exposed to radiant energy. However, Crookes never provided a true explanation for this.



http://en.wikipedia.org/wiki/William_Crookes  http://nientedinuovo.files.wordpress.com/2008/05/crookes.jpg

1829-1896
 * Friedrich August Kekule von Stradonitz**

Friedrich was a German organic chemist. He was the principal founder of the theory of chemical structure. This theory begins at the idea of atomic valence, and the ability of carbon atoms to link to each other, to the determination of the bonding order of all of the atoms in a molecule. Archibald Scott Couper arrived at the idea of self-linking of carbon atoms and provided the first molecular formulas where lines symbolize bonds connecting the atoms. Kekulé's most famous work was on the structure of benzene. In 1865 Kekulé published a paper in French stating that the structure contained a six membered ring of carbon atoms with alternating single and double bonds.

http://en.wikipedia.org/wiki/Friedrich_August_Kekul http://www.daviddarling.info/images/Kekule.jpg

http://www.windows.ucar.edu/cool_stuff/images/electron_cloud_sm.jpg http://www1.union.edu/newmanj/lasers/Light%20Production/Planetary%20Model.jpg

**1875- 1900**
__**Wilhelm Conrad Rontgen**__

year of discovery: 1895 nationality: German

Rontgen was born in Prussia in 1845 as an only child. he moved to the Netherlands an attended school but was expelled when he would not tell who drew a derogatory picture of one the teachers, and he could not be admitted into any other Dutch or German school. He was forced to continue his education elsewhere, and chose mechanical engineering, at the University of Zurich. In 1874 he was doing research on electrons using a Crooks tube and noticed that on a nearby table the was a fluorescent glowing screen. He was able to determine that there must be some type of invisible rays being emitted from the Crooks tube and penetrating the black paper. Because he discovered the rays but knew very little about them he named his discovery X-rays, a discovery which is instrumental to modern health care. He received the Nobel Prize in 1901. In 1923 he died but most likely of causes independent of exposure to radiation since he routinely used protective lead shields.

__**J.J. Thompson**__



year of discovery: 1897 country of origin: English

Joseph John Thompson was born in 1856 near Manchester England. His father died when he was only 16 years old. He attended Owens College, where, his math professor encouraged him to apply for the scholarship in math at Trinity College which is one of the most difficult and prestigious colleges at Cambridge University. He finished second in his class for mathematics, but he was offered a position to stay at the school and do research in the fields of math and science. Thompson is credited with the discovery of the electron, the isotope, and spectrometer. He received the Nobel prize for physics in 1906 for his discovery of the electron. He did a series of experiments using cathode tubes and rays, eventually discovering that the atom was not the smallest unit of matter, there are subatomic particles. He proposed the new, plum pudding model of an atom with negatively charged electrons and a positively charged space. He died in 1940 and was buried near sir Isaac Newton, who died of internal bleeding after being hit by an apple on the head.

On the left is the plum pudding model of the cell the J.J. Thompson proposed, with negitively charged electrons and a positively charged matrix in the atom. On the right is plum pudding, which Thompson most likely ate. In 1897 J.J. Thompson discovered the electron. He did this through a series of experiments with a cathode tube shooting cathode rays and testing the magnitism, properties of electrical energy, and mass compared to charge ratio. In 1904 he proposed the model of an atom on the right.

__**Antoine Henri Becquerel**__



year of discovery: 1896 nationality: French

Becquerel was a French chemist born in Paris in 1852. He was born into a family with a long line of well-known scientists and scholars. In 1888 he earned his degree of docteur-es-sciences. He discovered radioactivity by chance in 1896, when he left out uranium salts near photographic plates and discovered that the plates were fully developed. This lead him to discover spontaneous emission of nuclear radiation referred to as uranic rays. He was co-awarded the Nobel Prize, which he shared with two other scientists. He died in 1908 at the age of 56, most likely related to the heavy exposure to radioactive materials he had during his career.

**1900-1915** This is a picture of the first Solvay Conference in 1911 located in Brussels. It was the first physics conference ever held, a historic event, signifying the growing field of science at the time. Among those in attendance were, Marie Curie, Rutherford, and Albert Einstein, as well as many others.

__**Marie Currie**__

year of discovery: 1898 nationality: French

Marie Currie was born in Warsaw in 1867. She was educated in the local schools in the area, but she eventually decided it would be her best interest to leave Warsaw which was in a part of Poland being controlled by Russia at that time. She continued her education in Paris where she eventually became a professor of physics. She was an extraordinary scientist because she was the only woman trying to break into the boys club of science, and she did it better than many of the contemporary men. Along with her husband Pierre, she discovered Plonium and Radium by literally taking tons of pitchblend and over the course of several years and isolating the radioactive components. She deduced that there must be more than one radioactive element because she found an element far more radioactive than uranium. She challenged the thoughts of John Dalton and proposed that the idea of indestructible, invariable atoms, which chemistry to that point had been based on, was incorrect. She essentially rewrote the rules of chemistry. She was awarded with many prizes, including several Nobel Prizes. She died in 1934, most likely resulting from prolonged exposure to radioactive materials.



__**Ernest Rutherford**__

year of discovery: 1903 nationality: English

Rutherford was born in 1871 in New Zealand. He attended school at the University of New Zealand, and went to post graduate school in England at the University of Cambridge where he studied electronical technology. While there he held the world record, briefly, for the distance that electromagnetic waves were detected. He also coined the terms alpha and beta for the types of radiation given off by two elements, thorium and uranium. From 1900-1903, along with Frederick Soddy, he studied radioactive elements and determined that radioactivity was a result of atoms decaying, as Marie Curie proposed, and there is a certain formula to determine how long it will take for the atom to decay half way, a term refereed to as the half-life of an atom. This formula can prove to be useful, for instance, to find out the age of the earth, which is much older than scientists before the use of this method thought. This is the work that gained him the Nobel Prize, but he did not stop there. In 1909 he was involved with a project called the Greigor-Marsden Experiment. It showed the nuclear nature of atoms and lead Rutherford to formulate a new model of the atom. He used a cathode tube to shoot alpha rays through a thin peice of gold foil. According to the plum pudding model of atoms all of the alpha particles should have passed straight through the gold foil; the results were surprizing. Most of the alpha rays went straight through but a small percent were deflected from their path. Thompson's explanation was that atoms have concentrated centers of mass, and there is a definite electric field. He published his results in a 1911 paper, along with his new atomic model. In 1919 he used nuclear reactions to nitrogen into oxygen, becoming the first person to be able to do so. Later in his career, while working with Niels Bohr, he proposed the existance of neutrons providing a neutral charge with the same mass as the proton. He died in 1937 after an illustrious career.

__**Robert Millikan**__ year of discovery: 1908 nationality: American

Robert Millikan was born in Illinois, U.S.A. in 1868. He won the Nobel Prize in 1923 for his study in elementary electric charge and photoelectric effect. His major success was with the oil drop experiment. He measured the electron charge and proved that the charge is a constant not a average. He studied cosmic rays which he named, x-rays, and physical and electrical constants. He also reaffirmed Einstein's theory of photoelectric effect. He died of a heart attack in 1953 of a heart attack.



Millikan did his oil drop experiment in something like this.



1915-1950
year of discovery: 1926 nationality: Austrian
 * __Erwin Schrodinger__**

Erwin Schrodinger was born in Austria in 1887. Schrodinger did many independent studies and worked with other scientists, and in 1914 he achieved habilitation, which is the equivalent of a PhD, or degree of higher learning. Schrödinger began to think about explaining the movement of an electron in an atom as a wave. By 1926 he published his work, providing a theoretical basis for the atomic model that Niels Bohr had proposed based on laboratory evidence. The main equation of his publication became known as Schrödinger's wave equation. This was a paper on wave mechanics known as Annalen der Physik". The paper showed the correct energy values for the hydrogen atom. The paper is known as one of the most important achievements of the 20th century. This was the second theoretical explanation of electrons in an atom, following Werner Heisenberg's matrix mechanics. A split threatened among physicists, but Schrödinger soon showed that the two theories were identical, only expessed differently. He released 3 more papers, one solving the quantum harmonic oscillator and the rigid rotor, another gave treatment to the Stark effect, and the last showed how to treat problems in which the system changes with time. The papers made Schrodinger well known, and were the center of his achievements. He received the Nobel prize in 1933 for his extensive studies of Quantum Mechanics. He died in 1961.



__**Werner Heisenberg**__

year of discovery: 1925 nationality: German

Heisenberg was born in Germany in 1901. He was a theoretical physicist and is most well known for his uncertainty principle of quantum theory. He also made contributions to the theory of wave mechanics. He was attacked by the German press when Hitler came to power in 1933 and investigated by the SS. Along with two other scientists he developed the matrix formulation of quantum mechanics in 1925. He was awarded the Nobel Prize in 1932 for his contributions to science. He died of cancer in his home in Munich Germany in 1976.

__**James Chadwick**__

year of discovery: 1932 nationality: English

Born in Cheshire England in 1891, he attended school in Manchester. He was in Germany at the start of WWI and was taken prisoner by the German army and remained there for four years. When he was released he returned to England to continue his research and he became the head of Cambridge University's nuclear physics lab. Rutherford had postulated about the neutron in 1919 but Chadwick continued the research of the neutron and through experimentation discovered a neutral particle with relatively the same mass as the proton and no charge, proving its existence. He published his findings in a paper entitle "Possible Existence of Neutron" and he received the Nobel Prize in 1935 for his discovery. He paved the way towards nuclear fission and made it possible to create elements heavier than uranium. He died in 1974.

__**websites**__ http://www.aip.org/history/electron/jjthomson.htm http://nobelprize.org/nobel_prizes/physics/laureates/1903/becquerel-bio.html http://en.wikipedia.org/wiki/Henri_Becquerel http://en.wikipedia.org/wiki/J._J._Thomson http://www.aboutnuclear.org/view.cgi?fC=History,Hall_of_Fame,Wilhelm_Conrad_Rontgen http://en.wikipedia.org/wiki/Wilhelm_Conrad_Röntgen http://nobelprize.org/nobel_prizes/physics/laureates/1903/marie-curie-bio.html http://en.wikipedia.org/wiki/Ernest_Rutherford http://library.thinkquest.org/28582/bio/millikan.htm http://en.wikipedia.org/wiki/Werner_Heisenberg http://nobelprize.org/nobel_prizes/physics/laureates/1933/schrodinger-bio.html http://en.wikipedia.org/wiki/James_Chadwick http://www.thocp.net/biographies/chadwick_james.htm http://en.wikipedia.org/wiki/Plum_pudding_model

__**pictures**__ http://upload.wikimedia.org/wikipedia/commons/5/56/Danzig_Wilhelm_Konrad_R http://www.orau.org/PTP/collection/Radiology/barium6.jpg http://www.swanvalley.com.au/NR/rdonlyres/099F61FA-5AFB-448A-861B-237A113065DD/0/PlumPudding.JPG http://www.doe.mass.edu/mcas/images/db/07chemHSq25.gif http://www.manep.ch/img/photo/challenges/nanotubes/thompson.jpg http://photos.aip.org/history/Thumbnails/becquerel_henri_a3.jpg http://en.wikipedia.org/wiki/Henri_Becquerel http://en.wikipedia.org/wiki/Marie_Curie http://lovebscott.sharenow.com/wp-content/uploads/2008/07/marie-curie-eli0-030.jpg http://www.kodiakexp.com/_resources/pitchblende2.jpg http://periodictable.com/Samples/084.8/s9s.JPG http://www.aip.org/history/curie/brief/images/radium/ra.jpg http://goatley.co.nz/images/Sir%20Ernest%20Rutherford.jpg http://media-2.web.britannica.com/eb-media/75/22475-004-A3C9BDB8.gif http://upload.wikimedia.org/wikipedia/commons/a/a6/Robert-millikan2.jpg http://homepage.mac.com/dtrapp/chemGraphics.f/MillikanApparatus.jpg http://www.slac.stanford.edu/exp/mps/FCS/millikan.gif http://media-2.web.britannica.com/eb-media/82/22482-004-8AF21221.gif http://www.malaspina.com/jpg/schrodinger.jpg http://www.microscopyu.com/articles/optics/images/components/componentsfigure2.jpg http://www.starkeffects.com/images/stark_splitting.png http://www.geocities.com/vjeran_st1/af/fizika/Heisenberg/Heisenberg.gif http://www.ph.surrey.ac.uk/partphys/chapter2/images/chadwick.jpg http://users.zoominternet.net/~even/e_noyau.JPG http://www.teleamazonas.com/imagenes/contenido/nickmix/jimmy_neutron.jpg