Fall.2008MMA.Riley.Timeline

[|www.epicurus.info] Died: 271 BC Country of Origin: Greece Year of first major discovery: early-mid 200 BC Epicurus believes that the universe has always existed because something can not come from nothing. He believes the same idea for atoms. He believes they have always existed and can't just come to existence from nothing. He also says that the universe is an unlimited size. He says filling that is a limitless amount of atoms in a limitless void. If the void wasn't limitless atoms would be frozen and not be able to move. Many of his views are similar to those of Democritus; for example he believes that atoms have weight. He along with the other scientists of this time period were trying to give rationa; reasoning as to why things happened as they did. http://www.iep.utm.edu/e/epicur.htm
 * //Ancient Times (450 AD and Prior)://**
 * Epicurus:** Born: 341 BC

[|www.aetheoraem.com] Died: Unknown ~5th Century BC Country of Origin: Greece Year of first major discovery: Early 5th century BC Leucippus is best known for his theory of the universe. This theory had two parts, that one part of the universe was solid, while the other part of the universe is empty space. This claim set the stage for his pupil Democritus to propose an atomic theory. This theory was based on a claim that only things in the universe can exist from what they had, not what they didn't have. This makes sense, things are the way they are because of what they posses not by what they don't posses. Leucippus alsop believed that atoms were always in motion, and that because atoms were unchanging, they stayed the same forever. http://plato.stanford.edu/entries/leucippus/
 * Leucippus-** Born: Unknown

[|www.web.mit.edu] Died: 370 BC Country of Origin: Greece Year of first major discovery: around 300 BC Democritus is known for proposing an atomic theory, but he got his idea for the idea of an atomic theory from his teacher Leucippus. His theory was much more indepth and explained the physical world very well. He said that all matter ios composed of indestructible matter. He gave it the word atomos (that is where atom comes from.) He said that atoms remain constant which explains the universe remaining somewhat constant. His most famous quote is, "Nothing occurs at random, but everything happens for a reason and by necessity." http://www.iep.utm.edu/d/democrit.htm
 * Democritus-** Born: 458 BC

[|www.students.umf.maine.edu] Died: 1727 Country of Origin: England Year of First major discovery: 17th Century Isaac Newton believed like many other scientists of his time that all things were composed of atoms. However they couldn't be proven as a fact, only a theoy, no experiment could say for sure that they truely 100% exist. He believed light was composed of little tiny particles.Newton also gave us the laws of motion. Those paved the way for many discoveries. 1. A body at rest/in motion will stay at rest/in motion until acted upon by an outside force. 2. Force= mass*acceleration. 3. To every action there is an equal and opposite reaction. Those rules helped to rationalize some of the scientists ideas about the atom. http://www.lucidcafe.com/library/95dec/newton.html, www.**newton**.ac.uk/newtlife.html
 * //1700-1800:// **
 * Sir Isaac Newton-** Born: 1643

[|www.chem.gla.ac.uk] Died:1799 Country of Origin: France Year of first major discovery: 1750 Joeseph Black's most famous discovery was that of "fixed air." Today fixed air is known as carbon dioxide. He used a substance known as magnesia alba and burned it, the reaction released carbon dioxide. He then weighed the sample afterward to figure out the weight. He also discovered latent heat. Latent heat is a type of heat that makes a substance change state. This was the beginning to the study of thermodynamics. He also discovered the idea of specific heat which, along with latent heat, is important for anyone studying to be a marine engineer. http://www.chem.gla.ac.uk/~alanc/dept/black.htm
 * Joeseph Black-** Born: 1728

[|www.kta1-hasselt.be] Died: 1806 Country of Origin: France Year of first major discovery: 1779 Columb is best known for the columb which is an electrical unit of charge. However he did do some work in the chemistry field. He started by researching about the laws of friction, he went on to publish a book dedicated to them. After that he began to study using his torsin balance to distribute electricity over surfaces. He was able to study electrical and manetic action due to them. http://www.nndb.com/people/777/000091504/, http://www.geocities.com/bioelectrochemistry/coulomb.htm
 * Charles Augustin De Columb-** Born: 1736

**//1800-1875://** [|www.mayoclinic.org] Died: 1844 Country of Origin: England Year or first major discovery: 1808 John Dalton's biggest discovery was the set of elements he discovered. He was very close to some of the actual weights and names of the atoms. He understood that not all elements were the same size. He also came up with an Atomic Theory; it had four parts. 1.) All atoms are made of atoms which are indivisible and indestructable. 2.) All atoms of a given element have identical mass and properties. 3.) Compounds are formed by a combination of two or more different kinds of atoms. 4.) A chemical reaction is a rearrangement of atoms. Most of this theory is correct. However some parts are wrong, but this is very good for being a pioneer in the categorizing of atoms. http://www.chemheritage.org/classroom/chemach/periodic/dalton.html
 * John Dalton-** Born: 1766

[|www.ysfine.com] Died:1856 Country of Origin: Mexico Year of first major discovery: 1808 Avogadro is most famous for his number. His number is 6.02x10^23. This number is how many molecules are in 1 mol of a substance. This is important because if we want to do conversions to the number of atoms in a certain number of grams of mols of a substance this number gives us the ability to determine that. He also came up with Avogadro's law which states that masses of the same volume with different mass have a direct relationship to the molecular weight of them. http://www.bulldog.u-net.com/avogadro/avoga.html
 * Armedeo Avogadro-** Born: 1776

[|www.cultureofchemistry.blogspot.com] Died: 1923 Country of Origin: Germany Year of first major discovery: 1870 Roeentgen's first discovery was of specific heats of certain gases and then the conductivity of certain crystals. He also studied how electromagnetic fields react with planes of polarized light. His next most major discovery was that of the x-ray photo. While working one night he noticed that a piece of special paper glowed when it was put in front of a discharge tube. Seeing this he grabbed his wifes hand and put it in the path of the unknown rays. After a few secondshe let her hand go and developed the piece of paper. Oh it he made a remarkable discovery. His wife's hand blocked the rays which made her hand outline on the paper. The rays couldn't penetrate her skin or bones so they showed up black on the paper. For that discovery he was given the Nobel Prize. http://nobelprize.org/nobel_prizes/physics/laureates/1901/rontgen-bio.html
 * Wilhelm Roentgen-** Born: 1845

[|www.gardenofpraise.com] Died: July 4, 1934 Country of Origin: Poland Year of first major discovery:1896 Curie followed the discovery of Becqueril and studyed radiation. She really focused on Uranium and discoveryed the amount of radiation depended upon how much of the substance was present. She discovered radioactivity had little to do with the molecule's interaction but the atom itself. She also discovered a new element which she called polonium after her home country. She also discovered radium and coined the word radioactivity. http://nobelprize.org/nobel_prizes/physics/laureates/1903/marie-curie-bio.html
 * // 1875-1900: //**
 * Marie Curie-** Born: November 7, 1867

[|www.people.clarkson.edu] Died:1908 Country of Origin: France Year of first major discovery: 1896 His first work was on polarization of light and absorption of light by crystals. He also worked on magnetism on the stars. After these works he discovered that radioactivity occurs naturally. He sought to see if there was a connection between phosphorescense and radioactivity. He experiemented with salts, it was found that all Uranium salts fogged the plate. He discovered that the rays given off by uranium could be diflected therefore differing from x-rays. http://nobelprize.org/nobel_prizes/physics/laureates/1903/becquerel-bio.html
 * Henri Becquerel-** Born: 1852

www.britannica.com Died: 1937 Country of Origin: New Zealand Year of first major discovery: 1896 He started off by taking a look at how iron respended to oscillating waves. All the findings were published into a book. He designed a machine that worked at high frequency alternating currents. He worked closely with a man named Professor JJ Thompson. He worked with Thompson on studying x-rays and ions in an electric field. He discovered the existence of alpha and beta particles in radiation. Rutherford trying to prove his teacher right did the gold foil experiment. This experiment was done by shooting alpha particles toward a thin sheet of gold foil and seeing where they went. If Thompsons model of the atom were true then the particles would just go right through the foil; what actually happened shocked everyone.Most particles went through while other particles were deflected to the sides while some even bounced right back to him. He discovered the nucleus he said that most of the mass is in the nuclues even though it is small. http://nobelprize.org/nobel_prizes/chemistry/laureates/1908/rutherford-bio.html
 * Ernest Rutherford-** Born: 1871

www.kentchemistry.com Died: 1940 Country of Origin: England Year of first major discovery: 1903 Thompson first discovered the electron using the cathode ray tube. This athode ray tube was a vacuum in which particles travelled like light waves and they could be bent by magnets. However, JJ Thompson is best known for the plum pudding model of the atom. In this model Thompson thought that electrons floated freely in positively charged cloud. That is how there was no charge in an atom. But this theory was proven wrong by his student Rutherford. But the idea was very close to being right, he had found that they electons were negatively charged, hence why the atom is neutral. He was right but wrong at the same time. http://nobelprize.org/nobel_prizes/physics/laureates/1906/thomson-bio.html
 * // 1900-1915: //**
 * JJ Thompson-** Born:1856

[|www.amorosochem.tripod.com] Died: 1953 Country of Origin: USA Year of first major discovery: 1910 Robert Millikan is best known for his experiement with the oil droplets. He put droplets of oil through a pinhole beween two charged metal plates. He notices that some of the droplets continued to fall to the bottom plate, while others reversed directions and went back up, while some even floated in midair. This discovery was amazing, he had discovered that an electron had a charge of -1. This was remarkable because he began to make sence of what had been proposed by many of his predecessors in his field. He also gave us an atomic structure of electricity. He also studied the range of spectrum between ultraviolet rays and x-rays. All of which help to shape they way we think today. http://nobelprize.org/nobel_prizes/physics/laureates/1923/millikan-bio.html
 * Robert Millikan-** Born: 1868

www.mlahanas.de Died: Novemeber 18, 1962 Country of Origin: Denmark Year of first major discovery was 1912 Bohr did mostly theoretical work. He also wrote about the properties of metal based on the aid of electron theory. That study he conducted is still used widely today and is very important. His next task was to tackle "Plank's quantim theory of radiation." He began to study them and published an article in the Philosophical Magazine. This article was aboou the theoretical absorbtion of alpha rays. After that he begna to work on a study of atoms based on what Rutherford had gathered on the atomic nucleus. He is credited with giving us the first model of the atomic structure. He won the Nobel Prize for his work. he helped rationalize the thought that an atom could be split. He also clarified problems with physics due to his discoveries. He wrote over 100 publications. Boar laft Denmark during World War II and came to America to help with the Atomic Energy Project. He was against the atomic bomb, he wanted atom to be used for peaceful purposes only. http://nobelprize.org/nobel_prizes/physics/laureates/1922/bohr-bio.html
 * Niels Bohr**- Born: October 5, 1885

[|www.nobelprize.org] Died: 1976 Country of Origin: Germany Year of first major discovery: 1925 When Heisenberg began his research Bohr's theory was the most widely accepted idea of the atom. But a few areas of the theory were not very well explained and needed to be revamped. The biggest problem he needed to revamp was the nature of light. What does is do? How does it act? All these questions were questions Heisenberg was looking to answer. He also wanted to know, what the actually physical and chemical properties were of atoms, and how light reacts with molecules. So they did research and basically diecovered and came up with the idea of Quantum Mechanics. He had to come up with a whole new system of mathematics because the electron orbits couldnt be observed. He discovered the idea of matrices in math as well. http://nobelprize.org/nobel_prizes/physics/laureates/1932/heisenberg-bio.html
 * // 1915-1950: //**
 * Werner Heisenberg-** Born: 1901

www.humanthermodynamics.com Died: 1961 Country of Origin: Austria Year of first major discovery: 1926 Schrodinger helped to solidify Bohr's atomic model as being the truth. He gave concrete evidence by runnning experiments to show that it was the truth. He used what became known as Schrodinger's wave equation to prove Bohr correct. He also did work on the electrons in an atom using the matrices that Heisenberg discovered. People could visualize Schrodinger's model while they couldn't do that with Heisenber's ideas because they were to mathematically advanced for most people. People thought the ideas of the two scientists were different until they were shown by Schrodinger that they were the same ideas expressed differently. http://nobelprize.org/nobel_prizes/physics/laureates/1933/schrodinger-bio.html
 * Erwin Schrodinger-** Born: 1887

[|www.nobelprize.org] Died: July 24, 1974 Country of Origin: England Year of first major discovery: 1932 Chadwick is best known for the discovery of the neutron. That was such an important discovery because it had been thought that there was only positive and negative charges in an atom. This helped to solidify and prove the idea of atomic mass and charges. He helped pave the way for the idea and the action of spliting atomic nuclei. He inadvertanltly helped start the developmentof the atomic bomb. He was placed at the head of the Manhattan Project, which developed the atomic bomb. This was major because it ended up ending World War II with a limited amount of casualities to the US side because to fight Japan would have been bloody. By his discovery and research as the head of the Manhattan Project he saved countless American lives. http://nobelprize.org/nobel_prizes/physics/laureates/1935/chadwick-bio.html
 * James Chadwick-** Born: October 20, 1891

https://reich-chemistry.wikispaces.com/S.+Levey+Time+Line+Project?f=print Small, spherical, solid, indivisible model: This model was developed by Democritus. This is the most basic model of the atom. It was a rough idea, with what he had for technology this was good. He was right on a few things about the atom. First it is very small, one of the smallest things we can detect. Second it is a sphere for the most part, not completely true but for the most part it is right. Third is solid, he was wrong on this one, the atom is mostly small space. Indivisible is the last property, this is mostly true although you can get rid of electrons if done a certain way. http://home.comcast.net/~chemgirl2/Atomicnotes.html, http://hi.fi.tripod.com/timeline/ https://reich-chemistry.wikispaces.com/S.+Levey+Time+Line+Project?f=print Electron Cloud Model: This model was developed by Erwin Schrodinger based on Bohr's model of the atom. This model shows where an electron can be at any one second (the lighter red dots to the outside represent those.) The bright red dot in the center is the nucleus. http://www.regentsprep.org/Regents/physics/phys05/catomodel/cloud.htm
 * //Important models of the atom://**

[|www.commons.wikimedia.org] Plum Pudding Model: The plum pudding model was developed by JJ Thompson. This model as shown by the picture suggests that little electrons float around in a positive mass. That is where it gets the name plum pudding, the pudding is the positive and the plums are the positive charges. http://scienceworld.wolfram.com/physics/PlumPuddingModel.html, http://library.thinkquest.org/28582/history/plum.htm [|www.education.jlab.org] Rutherford Model: Rutherford was JJ Thompson's student as stated before and he wanted to prove his professor right on the thoery of the atom, so he preformed the gold foil experiment. (A picture of the experiment is under Rutherford's bio.) When the alpha particles reflected he realized that something must be taking up space in the atom. He developed a theory of the nucleus being in the center. That is the model we see today. http://www.iun.edu/~cpanhd/C101webnotes/modern-atomic-theory/rutherford-model.html www.hcc.mnscu.edu Planetary Model: Bohr is credited with coming up with this model. In his model as depicted above atoms revolve around the nucleus and they go in many different directions. Their orbits go around the nucleus but can't get outside the pull toward the center. This pull keeps the atom together. Rutherford and Bohr's model are very, very similar. http://csep10.phys.utk.edu/astr162/lect/light/bohr.html