1. Period 5.

2. Scientist’s Early Theories on the Atom By Corey Lacher and Grant Miller

3. Democritus He was born into considerable wealth which allowed him to travel and research more than a common citizen He studied in Egypt at the ancient schools, which specialized in philosophy and mathematics. After he finished his studies, he was impoverished and considered insane among his people. Leucippus was Democritus’ mentor. http://www.nndb.com/people/790/000087529/ my.opera.com

4. Leucippus His date of birth or his parents’ status is unknown, however it is estimated that he was born into the upper middle class A lot of Leucippus’ theories are to contradict his teacher, Zeno After growing up, he moved to Abdera where he began his own studies with his student Democritus. http://plato.stanford.edu/entries/leucippus/#2 reich-chemistry.wikispaces.com

5. Democritus Atomic and Leucippus Theory Because of the close relationship between Leucippus and Democritus, their atomic theories are very alike. The first theory, created by Leucippus said there is an infinite amount of two elements, the solids and the void. This theory was changed during Democritus’s studies, and finally published. http://plato.stanford.edu/entries/leucippus/#2

6. Atomic Theory Proposed atomic theory of matter Proposed that contrary to belief matter could not be divided forever Proposed the idea of an atom-the smallest matter can be divided and still be the same substance http://www.funsci.com/fun3_en/democritus/democritus.htm

7. Aristotle Greek philosopher Student of Plato, teacher of Alexander the Great Educated as aristocracy Physics, Metaphysics, Nicomachean Ethics, Politics, De Anima (On the Soul) and Poetics, important works Studied many sciences Scientific method http://en.wikipedia.org/wiki/Aristotle britannica.com.ph

8. Atomic Theory Proposed matter can divided infinitely Due to being highly regarded as scholar, stuck for 2000 years http://cstl-csm.semo.edu/mcgowan/ch181/atomhist.htm

9. Antoine Lavoisier and The Law of Conservation of Matter By John Chiavelli and Joey Miller

10. Biography Born to a wealthy Paris family and completed a degree in law He dreamed of studying mathematics and science, and soon gained membership into France’s most prestigious Science Academy He married Marie-Anne Pierrette Paulze, who became his scientific colleague She translated notes, drew sketches, and developed a scientific mind

11. Continued… Known for the Law of Conservation of Matter/Mass Implemented the Metric System in France Would go on to be the architect of the chemistry revolution Known as the Father of Modern Chemistry Guillotined at age 51, found guilty of conspiracy against the people of France

12. The Phlogiston Theory Chemistry was very underdeveloped at the time A weightless or nearly weightless substance known as phlogiston. Metals and fire were considered to be rich in phlogiston and earth was considered oxygen poor Stated that weight loss during combustion was a result of a loss of phlogiston When metal is calcined, or roasted in the presence of air, it turns to a powdery substance called a calx However, when some metals were calcined, the resulting calx was heavier than the initial metal Scientists tried to come up with explanations, but the theory was WRONG***

13. The Law of Conservation of Matter/Mass Was an anti-phlogistonist Designed an experiment to disprove the theory He heated mercury in a jar for 12 days, red mercury calx formed, and the volume of air in the jar decreased The remaining air was nitrogen, and heating the calx produced the air that had decreased The sequence of experimentation established that heat caused the formation of calx, and stronger heating reverted it back to the original substances Hg(l) + O2(g) -> HgO(s) and then HgO(s) -> Hg(l) + O2(g) THEORY DISPPROVED

14. ***The law of conservation of matter states that matter is neither lost nor gained in traditional chemical reactions; it simply changes form.*** The state in which a substance is may change in a chemical reaction, for example, from a solid to liquid to a gas but its total mass does not change.

15. Significance of Concept Changed chemistry from qualitative to quantitative science Put an end to the Phlogiston Theory, by proving that the mass of the reactants is equal to that of the products He later showed that oxygen was responsible for weight differences associated with combustion

16. Continued… Acceptance of the Phlogiston Theory dissipated The Law of Conservation of Matter became accepted A major turning point in the world of chemistry Chemistry further developed into a vast scientific field Antoine Lavoisier is known as the Father of Modern Chemistry

17. Joseph Proust. Born on Sept. 26, 1754 in Angers, France. His father was apothecary of Angers. Studied chemistry in father’s shop. Became apothecary at prestigious Salpetriere hospital. Taught chemistry with famous chemist and physicist Pilâtre de Rozier http://en.wikivisual.com/index.php/Joseph_Proust http://www.answers.com/topic/joseph-proust

18. Joseph Proust’s Later Life. Went to Spain to teach at Chemistry School of Segovia and University of Salamanca. Napoleon invaded Spain and his army burnt Proust’s laboratory. Forced to go back to France as a result. Died on July 5, 1826 in Angers. During his lifetime, studied the sugars in fruits and vegetables (glucose) and created the Law of Definitive Proportions http://iml.jou.ufl.edu/projects/fall0 3/pfeiffer/university.htm http://en.wikipedia.org/wiki/Joseph_Proust

19. Law of Definite Proportions -A chemical compound contains the same proportions of elements by mass -All of one type of compounds have the same make up -Ex:The mass of Pure water is always 8/9ths oxygen and 1/9 hydrogen -Makes up part of modern chemistry

20. Law of Definite Proportions (Exceptions) -The law is not always true -Non-stoichiometric compounds composition can vary from sample to sample -Chemical Compounds with compositions that can not be defined by ratios of real numbers -Ex:Iron Oxide Wustile- Levels and mass of oxygen and iron can differ http://en.wikipedia.org/wiki/Law_of_definite_proportions

21. Effect Upon Chemistry Society Initially upon first publish there was much controversy among fellow chemists especially Berthollet, who believed the opposite of what Proust was trying to say; elements could come in any proportion. The laws of definite proportion created the basis for the development of the atomic theory by John Dalton mere years later. Dalton also came up with the law of multiple proportions, which in combination with the law of definite proportions, helped to begin stoichiometry (the science of chemical reactions).

22. Effect Upon Chemistry Society (cont’d) His law helped lead to chemists being able to create compounds and learn their properties more because knowing the ratio of elements is all they need. Naturally its also useful in identifying compounds. - For example, we know that Steel is always almost completely made of Iron with a bit of Carbon and other small elements. Although it is a chemistry principle it does have its practical uses. This law makes it easy to modify a baking recipe according to the amount you want to produce. http://en.wikipedia.org/wiki/Law_of_definite_proportions http://www.britannica.com/EBchecked/topic/480555/Joseph-Louis-Proust/260847/Law-of-definite-proportions http://www.ehow.com/about_4570091_law-definite-proportions.html

23. John Dalton Born: September 6th, 1766 in Eaglesfield, England Died: July 27th, 1844 of a stroke English chemist and physicist http://www.universetoday.com/38193/john-daltons- atomic-theory/ http://dl.clackamas.edu/ch104-04/dalton%27s.htm http://www.nndb.com/people/278/000049131/

24. Background Information Had two siblings: Jonathon and Mary Was a farmer for two years Discovered color blindness Learned math from a distant relative, Elihu Robinson Went to work at a school in Kendal for his cousin George Became a teacher at York College Is most widely known for his atomic theory

25. Dalton’s Atomic Theory Elements are made of small particles called atoms. All atoms for a particular element are identical and have the same mass. Atoms of different elements can combine in a chemical reaction to form chemical compounds in fixed ratios. [In a chemical reaction] atoms cannot be created or destroyed; only rearranged.

26. The Atomic Theory: Explanation/Significance It explains a lot of chemical properties; for example, how atoms can combine to form molecules It explains chemical change better than previous theories (the Particle Theory) had It confirms the basic laws of chemistry: Definite Proportions and Conservation of Mass

27. The Law of Multiple Proportions --Also known as “Dalton’s Law” -- It is part of what laid the foundation for Dalton’s atomic theory, and the basis of chemical formulas for compounds -States that when elements combine in more than one proportion, they do so in the ratio of small who numbers (under the assumption that they have the same type of chemical bond) --Example: carbon and oxygen react to form CO or CO2, but not CO1.4

28. Law of Multiple Proportions (continued) Example: 2 carbon oxides: CO and CO2 The ratio for the first is 1/1 The ratio for the second is 1/2 The ratio between these ratios is a ratio between small whole numbers, or 1/1 : 1/2= 2:1 - This proves that the law is consistent with the use of chemical formulas

29. JJ THOMSON CATHODE RAY TUBE Full Name: Joseph John Thomson December 18, 1856 – August 30 1940 Born in Cheetham Hill in Manchester, England Private School Education Attended Owens College at age 14

30. Transferred to Trinity College after his father died Became Cavendish Professor of Physics, with Ernest Rutherford as a student Married Rose Elizabeth Paget, daughter of a physician, and fathered one son and one daughter Seven of his research assistants got Nobel Prizes and his son won in 1937 for proving the wavelike properties of electrons He was awarded the Nobel Prize in 1906 in recognition of the great merits of his theoretical and experimental investigations on the conduction of electricity by gases In 1918 he became master of Trinity College, Cambridge and remained there until his death in 1940 JJ THOMSON

31. CATHODE RAY TUBE Thompson investigated the nature of matter which led him to create an experiment testing a charged particle In the Cathode Ray Tube, an electric current generates a beam that strikes through a hole on the other end of the tube A fluorescent coating is added to the ray to make it visible to human eyes There is a magnetic field around the ray, proving that it has mass The rays path is also affected by an external electric field, determining that the ray is charged

32. CATHODE RAY TUBE By studying the deflections of the tube due to the fields, Thompson determined the mass to charge ratio of the beam particles He found the mass-to-charge ratio to be thousands of times smaller than hydrogen, the lightest element, meaning they were extremely light or very highly charged He discovered that the beam was negatively charged

33. SIGNIFICANCE his research proved the existence of negatively charged particles, later called electrons proved atoms can be divided Created the plum pudding model of the atom which was later proved wrong by Ernest Rutherford Lead to later experiments with the electron

34. SIGNIFICANCE Contribution in the development of cathode ray tubes Lead to research in subatomic particles When a solid object was put in the path of cathode rays a shadow appeared showing that cathode rays traveled in straight lines. The cathode rays were deflected by electric and magnetic fields meaning they were composed of charged particles. When a paper wheel was placed in the path of the cathode rays, the cathode rays struck it and made it rotate, proving that cathode rays were made of particles

35. Robert Milikan Background: -March 22, 1868 - December 19, 1953 -Went to high school in Iowa (lived in a rural era) -Went to Oberlin College and then Columbia University -Wife = Greta Erwin Blanchar -Three sons: Clark Blanchard, Glenn Allen, and Max Franklin -Received his Ph.D. in 1895 -Made numerous discoveries in the fields of electricity, optics, and molecular physics (contributions to science were with the research of cosmic rays). -Was an author (wrote in scientific journals) that were really well- respected in science community

36. Robert Milikan Background: Held highly esteemed scientific positions: President of the American Physical Society Vice-President of the American Association for the Advancement of Science Held honorary doctor’s degrees from 25 universities Set a goal to write textbooks that would capture the attention of readers that was easy to understand Vice-Chairman of the National Research Council during WWI playing a major part in developing anti-submarine and meteorological devices

37. The Experiment: Oil-Drop -Major success was determining charge of an electron, using the elegant "falling-drop method" called Milikan Oil Drop -Proved that electric charge is quantized (as predicted by quantum physics) -Discovery was accomplished by spraying minute drops of oil into a specially built chamber

38. The Experiment: Oil-Drop -How the experiment operated: 1.Atomizer produces oil droplets 2.Oil Droplets fall through the hole 3.X-rays negatively charge the droplets 4.Voltage applied to 2 plates creates an electric field and the electric force pulls some oil drops up 5.Microscope measures the rate at which the oil drops fall or rise

39. The Experiment: Oil-Drop -Drops travel up/down depending on the forces acting on it - 1st: experiment is done without an electric field = gravity pulls the drops down because its force is greater than air resistance - Then done W/ electric field = electric force larger than gravitational pull causing droplets to go up -Using this formula: you can find velocity (velocity is related to charge), thus finding the charge of an electron W/O Electric Field W/ Electric Field

40. Significance of the Experiment -First successful scientific attempt to detect and measure the effect of an individual subatomic particle -The Millikan oil drop experiment was so significant that Millikan won the 1923 Nobel Prize in physics for his work Add picture here

41. Significance of the Experiment -Expanded upon Cathode-Ray experiment which determined mass/charge ratio but didn’t determine the numbers for it - He determined the numbers for the ratio -Determined charge of electron through oil-drop experiment -Determined that an electron is a sub- atomic particle -Determined that charge is quantized http://www.goalfinder.com/product.asp?productid=69

43. 1871- 1937 “Father of nuclear physics” Early on in his life, he developed a device to detect electromagnetic waves Left home in New Zealand to study at Caterbury University as a research student on a scholarship His professor, J.J. Thompson recognized his potential and invited Rutherford to work with him

44. After radioactive atoms were discovered, he became highly interested in radioactivity He discovered that radioactive atoms gave off two different types of rays: alpha and beta rays (alpha= made up of positively charged particles; beta= made up of negatively charged particles Returned to New Zealand for marriage but continued his research at McGill University He researched into radioactivity, discovering radon Published the book, Radioactivity, and won the Noble Prize in chemistry for his work on the transmutation of elements and the chemistry of radioactive substances Is most famous for his Gold Foil Experiment

45. Rutherford came up with the earliest version of the atomic model when he conducted his gold foil experiment When firing alpha particles at a fine sheet of gold foil, he found that some particles pass through the foil, while some change direction or pass back He concluded that the atoms of gold foil must be mostly empty space around a dense nucleus and came up with his atomic model

47. 1.Downfall of the Plum Pudding Model 2.Creation of the Atomic Model

48. J.J Thompson’s Plum Pudding Model claimed that the negatively charged electrons were embedded in a sphere of positive charge so the charges were balanced WAS INCORRECT since none of Thompson’s electrons contained enough charge or mass to deflect alphas strongly ** INSTEAD, Rutherford suggested in his Atomic Model that a large amount of the atoms charge and mass is instead concentrated into a very small region giving it a high electric field Rutherford propsed that the atom was mostly empty space

50. Sir James Chadwick 1891 - 1974

51. Early Life Born October 20, 1891 Born in Cheshire, England Graduated from Honours School of Physics in 1911 Studied under Ernest Rutherford in the Physical Laboratory in Manchester for 2 years Gained his Master of Science degree in 1913

52. Scientific Context Ernest Rutherford recently discovers the proton Henri Becquerel recently discovers gamma waves Beginning to develop accurate atomic model

53. Experiment Sample of Beryllium bombarded with alpha particles (type of radiation) Caused Beryllium to emit different radiation Knew radiation was neutral because it was not affected by a magnetic field Knew the particles were large because they discharged protons

54. Experiment

55. Discoveries Leads to discovery of the neutron (1932) Discovers mass of the neutron

56. Significance Previously, mass number was always much higher than atomic number Neutrons solved this problem Atomic model more accurate Receives Nobel Prize in Physics in 1935 Knighted in 1945

57. Significance Made the development of the atomic bomb possible Now understood how isotopes worked Used uranium 235 to create bomb Chadwick worked on Manhattan Project

58. Niels Bohr and the Bohr Model By Tim Hwang and Noah Pardes Born: October 7, 1885 Died: November 18, 1962 http://www.lucidcafe.com/library/95oct/nbohr.html

59. About Niels Bohr Born in Copenhagen, Denmarck on October 7, 1885 His father is Christian Bohr who was a professor of physiology at the University of Copenhagen. His mother is Ellen Adler Bohr. His brother is Harald Bohr who was a mathematician Enrolled as an undergrad at the University of Copenhagen in 1903 and graduated with a doctrine in 1911. Marries Margrethe Nørlund in 1912.

60. About Niels Bohr Cont. In 1913, he published his theory on the structure of the atom which was based on Rutherford’s theory. Niels Bohr becomes the professor of physics at the University of Copenhagen in 1916. He died in Copenhagen on November 18, 1962

61. Main Point Electrons orbit the nucleus in orbits that have a set size and energy. The energy of the orbit is related to its size. The lowest energy is found in the smallest orbit. Radiation is absorbed or emitted when an electron moves from one orbit to another. The simplest example of the Bohr Model is for the hydrogen atom (Z = 1) or for a hydrogen-like ion (Z > 1), in which a negatively-charged electron orbits a small positively-charged nucleus-char

62. Main Point Cont. When an electron is in an "allowed" orbit it does not radiate. Thus the model simply throws out classical electromagnetic theory When an electron absorbs energy from incident electromagnetic radiation, it "quantum jumps" into a higher energy allowed state. This higher energy state corresponds to an allowed orbit with a higher value of the integer n When an electron is in a higher energy state, it can quantum jump into a lower energy state, one with a smaller value of n, emitting all of its energy as a single photon of electromagnetic energy

63. Significance The significance of the Bohr model is that it states that the laws of classical mechanics do not apply to the motion of the electron about the nucleus Bohr proposed rather that a new kind of mechanics, or quantum mechanics, describes the motion of the electrons around the nucleus The Rutherford-Bohr model provided the first really useful view of the atom It matched what scientists knew about chemical reactions and the way atoms behaved

64. Significance Cont. It matched what scientist knew about chemical reactions and the way atoms behaved The Bohr model of the atom deals specifically with the behavior of electrons in the atom While he realized electrodynamics is useless, he proposed to use "mechanics" to describe the motion of an electron in its orbit

65. Work Cited http://www.lucidcafe.com/library/95oct/nbohr.html http://en.wikipedia.org/wiki/Niels_Bohr http://nobelprize.org/nobel_prizes/physics/laureates/1 922/bohr-bio.htmlhttp://nobelprize.org/nobel_prizes/physics/laureates/1 922/bohr-bio.html http://chemistry.about.com/od/atomicstructure/a/bohr- model.htmhttp://chemistry.about.com/od/atomicstructure/a/bohr- model.htm http://www.upscale.utoronto.ca/PVB/Harrison/BohrM odel/BohrModel.htmlhttp://www.upscale.utoronto.ca/PVB/Harrison/BohrM odel/BohrModel.html http://www.lycos.com/info/bohr-model--electrons.html http://www.chemteam.info/Electrons/Bohr-Model- part1.htmlhttp://www.chemteam.info/Electrons/Bohr-Model- part1.html

66. Citations http://www.visionlearning.com/library/module_viewer. php?mid=56http://www.visionlearning.com/library/module_viewer. php?mid=56 http://mattson.creighton.edu/History_Gas_Chemistry/ Lavoisier.htmlhttp://mattson.creighton.edu/History_Gas_Chemistry/ Lavoisier.html http://cti.itc.virginia.edu/~meg3c/classes/tcc313/200R projs/lavoisier2/home.html#phlogistonhttp://cti.itc.virginia.edu/~meg3c/classes/tcc313/200R projs/lavoisier2/home.html#phlogiston

67. Citations - http://martine.people.cofc.edu/111LectWeek1.htm?referrer=webcluster& -http://en.citizendium.org/wiki/Image:Carbon_ with_oxygen.JPG -http://www.iscid.org/encyclopedia/Law_of_M ultiple_Proportions -http://dictionary.reference.com/browse/law+o f+multiple+proportions -http://www.brightstorm.com/science/chemistr y/matter/law-of-definite-proportions-law-of- multiple-proportionss

68. http://www.solarpowerwindenergy.org/wp- content/uploads/2009/05/kineticandpotentialenergy.j pg http://library.thinkquest.org/3659/energy/matterandene rgy.html http://www.visionlearning.com/library/module_viewer.p hp?mid=56 http://cti.itc.virginia.edu/~meg3c/classes/tcc313/200Rp rojs/lavoisier2/home.html#phlogiston http://mattson.creighton.edu/History_Gas_Chemistry/Lavoisier. html http://sciencepark.etacude.com/chemistry/law.php http://www.ehow.com/about_4568411_law- conservation-mass.html http://www.britannica.com/EBchecked/topic/684121/ch emical-bonding/43364/The-law-of-conservation-of- mass http://www.homeoint.org/morrell/articles/pm_origin.htm http://www.ssplprints.com/image.php?id=100610 http://en.wikipedia.org/wiki/Wikipedia:Featured_picture_candidates/Antoine_Lavoisier http://commons.wikimedia.org/wiki/File:Lavoisier_decomposition_air.png http://cstl-csm.semo.edu/mcgowan/ch181/atomhist.htm http://www.famousdead.com/antoine-lavoisier/ http://www.scienceshorts.com/lavois.htm http://www.iss.k12.nc.us/schools/mountmourne/lalerch/shmetric.htm http://letsgotribe.mlblogs.com/archives/2007/10/the_tribe_pulls.html http://www.rjdposters.com/Store/DrawProdu cts.aspx?Action=GetDetails&ProductID=621 &ParentID=&PageID=75 http://www.philiplarson.com/e1.shtml http://reich-chemistry.wikispaces.com/timothy.hitchings.atomichistory.fall.2009 http://www.daviddarling.info/encyclopedia/C/combustion.html http://www.silkywater.com/waterintro.htm https://www.msu.edu/~moorean4/TestSite/chemistrymain.htm http://www.mpch-mainz.mpg.de/~sander/chem-intro.html http://www.proprofs.com/quiz-school/story.php?title=periodic-table-quiz

69. http://en.wikipedia.org/wiki/J._J._Thomson http://www.experiment-resources.com/cathode-ray.html http://members.chello.nl/~h.dijkstra19/page3.html http://www.tutorvista.com/physics/jj-thomson-cathode-ray-tube freepatentsonline.com http://www.kentchemistry.com/links/AtomicStructure/JJThomps on.htm http://www.wwnorton.com/college/chemistry/gilbert2/tutorials/ interface.asp?chapter=chapter_02&folder=cathode_ray SOURCES Thomson

70. Citations Millikan http://www.goalfinder.com/product.asp?productid=69 http://www.juliantrubin.com/bigten/millikanoildrop.html http://chemistry.about.com/od/electronicstructure/a/millikan-oil-drop- experiment.htm http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/ryan_mcallister/slide3.htm

71. http://christchurchcitylibraries.com/kids/famo usnewzealanders/ernest.asp http://christchurchcitylibraries.com/kids/famo usnewzealanders/ernest.asp http://en.wikipedia.org/wiki/Ernest_Rutherford http://mysciencearticles.com/page/8/ http://www.britannica.com/EBchecked/topi c-art/41549/18103/Shell-atomic-model-In-the- shell-atomic-model-electrons-occupy http://www.britannica.com/EBchecked/topi c-art/41549/18103/Shell-atomic-model-In-the- shell-atomic-model-electrons-occupy http://picasaweb.google.com/lh/photo/HTbt GA9m7iMKVP8ry_drhw http://picasaweb.google.com/lh/photo/HTbt GA9m7iMKVP8ry_drhw http://reich- chemistry.wikispaces.com/Fall.2008.MMA.Hale y.Timeline http://reich- chemistry.wikispaces.com/Fall.2008.MMA.Hale y.Timeline http://www.natlib.govt.nz/collections/online- exhibitions/20th-century-scientists/ernest- rutherford http://www.natlib.govt.nz/collections/online- exhibitions/20th-century-scientists/ernest- rutherford

72. Sources Chadwick http://www.suite101.com/content/the-discovery-of- the-neutron-a46060http://www.suite101.com/content/the-discovery-of- the-neutron-a46060 http://nobelprize.org/nobel_prizes/physics/laureates/1 935/chadwick-bio.htmlhttp://nobelprize.org/nobel_prizes/physics/laureates/1 935/chadwick-bio.html Portrait: http://nobelprize.org/nobel_prizes/physics/laureates/1 935/chadwick-bio.html http://nobelprize.org/nobel_prizes/physics/laureates/1 935/chadwick-bio.html Nobel Prize Image: http://startswithabang.com/?p=982 http://startswithabang.com/?p=982 Rutherford Image: http://www.mlahanas.de/Physics/Bios/ErnestRutherfo rd.html

73. Sources http://en.wikipedia.org/wiki/Neutronz http://hyperphysics.phy- astr.gsu.edu/hbase/particles/neutrondis.html http://www.suite101.com/content/the-discovery-of- the-neutron-a46060 Becquerel Image: http://nobelprize.org/nobel_prizes/physics/laureat es/1903/becquerel-bio.html Mushroom Cloud Image: http://www.allamericanpatriots.com/photos/mushr oom-cloud