1.Chapter 3: Learning Objectives Explain the electrical properties of the atom. Describe how the properties of electricity explain the structure of atoms. Describe the experiments that led to the discovery of X-Rays and an explanation ofradioactivity. Distinguish the three main types of radioactivity: alpha, beta and gamma. Sketch the nuclear model of the atom and identify its parts. List the particles that make up the nucleus of an atom and give heir relative masses andelectric charges Identify elements and isotopes from their nuclear particles. Define quantum. Arrange the electrons in a given atom in energy levels, (shells). Relate the idea of a quantum of energy to an orbital. Write an electron configuration, (in subshell notation), for a given atom. Describe how an elements electron configuration relates to its location in the periodic table. Distinguish the conversion of solar energy into electrical energy in a solar cell from theconversion of solar energy into the chemical bond energy of a solar fuel. Explain why splitting water into the elements hydrogen and oxygen requires an energy inputand producing water by the reaction of hydrogen and oxygen produces water. 2013 Pearson Prentice Hall, Inc.

2. Atomic Structure: Electricity and the AtomElectrolyte: A compound that conducts electricity whenmolten or dissolved in water.Electrodes: Carbon rods or metallic strips that carryelectrical current. 2013 Pearson Education, Inc. Chapter 3 2 3. Electrolysis & Aluminum Synthesis:Charles Martin Hall pictured below was an American chemist, who discovered an inexpensive method for the isolation of purealuminum from its compounds. The same electrolytic process was discovered concurrently by the French chemist Paul L.T.Heroult and is therefore known as the Hall-Heroult process. It became the basis for the aluminum industries both in the UnitedStates and in Europe. Hall was born in Thompson, Ohio, on December 6th 1863. He became interested in chemistry, and more specifically in finding an inexpensive method for producing aluminum. While an undergraduate at Oberlin College. After his graduation in 1885, Hall set up laboratory at home and began work on the purification of aluminum. He had the idea that if he could find a non-aqueous solvent for aluminum oxide, he could produce metallic aluminum by electrolysis, using carbon electrodes. On Feb. 23, 1886, Hall found that molten cryolite, which is the mineral sodium aluminum fluoride, was the solvent he needed for the process; using the cryolite and aluminum oxide and homemade batteries, he produced his first small globules of aluminum. 4. ElectrolysisAnode: A positive electrode.Cathode: A negativeelectrode. 2013 Pearson Education, Inc. Chapter 3 4 5. IonsIon: An atom or group of atoms with a charge.Anion: A negative ion.Cation: A positive ion. 2013 Pearson Education, Inc. Chapter 35 6. Cathode Ray TubesMid-1800s: Crookess tube (Cathode Ray Tube) 2013 Pearson Education, Inc.Chapter 36 7. Thomson Experiment1897, Joseph John Thomson: Plum Pudding ModelDetermined the charge: Mass ratio of cathode rays(discovered electrons). http://www.youtube.com/watch?v=O9Goyscbazk 2013 Pearson Education, Inc.Chapter 37 8. Goldsteins Experiment: Positive Particles1886, Goldstein:Observed positive raysusing a perforated cathode. 2013 Pearson Education, Inc. Chapter 3 8 9. Eugen Goldstein In the mid-nineteenth century, Julius Plcker investigated the light emitted in discharge tubes (Crookestubes) and the influence of magnetic fields on the glow. Later, in 1869, Johann Wilhelm Hittorf studieddischarge tubes with energy rays extending from a negative electrode, the cathode. These rays produceda fluorescence when they hit a tubes glass walls, and when interrupted by a solid object they cast a shadow. In the 1870s Goldstein undertook his own investigations of discharge tubes, and named the light emissionsstudied by others kathodenstrahlen, or cathode rays. He discovered several important properties of cathoderays, which contributed to their later identification as the first subatomic particle, the electron. He found thatcathode rays were emitted perpendicularly from a metal surface, and carried energy. He attempted tomeasure their velocity by the Doppler shift of spectral lines in the glow emitted by Crookes tubes. In 1886, he discovered that tubes with a perforated cathode also emit a glow at the cathode end. Goldsteinconcluded that in addition to the already-known cathode rays, later recognized as electrons moving from thenegatively-charged cathode toward the positively-charged anode, there is another ray that travels in theopposite direction. Because these latter rays passed through the holes, or channels, in the cathode, Goldsteincalled them Kanalstrahlen, or canal rays. They are composed of positive ions whose identity depends on theresidual gas inside the tube. It was another of Helmholtzs students, Wilhelm Wien, who later conductedextensive studies of canal rays, and in time this work would become part of the basis for mass spectrometry. The anode ray with the smallest e/m ratio comes from hydrogen gas (H 2), and is made of H+ ions. In otherwords this ray is made of protons. Goldsteins work with anode rays of H+ was apparently the firstobservation of the proton, although strictly speaking it might be argued that it was Wien who measured thee/m ratio of the proton and should be credited with its discovery. Goldstein also used discharge tubes to investigate comets. An object, such as a small ball of glass or iron,placed in the path of cathode rays produces secondary emissions to the sides, flaring outwards in a mannerreminiscent of a comets tail. See the work of Hedenus for pictures and additional information. [2] 10. Electron Charge 1909, Robert Millikan: Using the oil-drop experiment, Millikan determined the charge of an electron. 2013 Pearson Education, Inc.Chapter 310 11. Plum Pudding Model 2013 Pearson Prentice Hall, Inc. 3/11 12. X-Rays1895, WilhemRoentgen:Using a cathode raytube, Roentgendiscovered X-rays. 12 13. 1895, Antoine Becquerel: Radioactivity-Gamma Rays Shortly after the discovery of x-rays, another form of penetrating rayswas discovered. In 1896, French scientist Henri Becquerel discovered naturalradioactivity. Many scientists of the period were working with cathoderays, and other scientists were gathering evidence on the theory that theatom could be subdivided. Some of the new research showed that certain types of atomsdisintegrate by themselves. Henri Becquerel discovered thisphenomenon while investigating the properties of fluorescent minerals. One of the minerals Becquerel worked with was a uraniumcompound. Uranium ore produces naturally occurring gammaradiation. Becquerels discovery was, unlike that of the x-rays, virtually unnoticedby laymen and scientists alike. It was not until the discovery of radiumby the Curies two years later that interest in radioactivity becamewidespread. After that Becquerel won a Nobel Prize and used his prize money toconveniently produce gamma radiation to transform himself into theIncredible Hulk. His son, Bruce Banner went on to fame on the staff ofMarvel Comics.http://www.nobelprize.org/nobel_prizes/physics/laureates/1903/becquerel-bio.html 2013 Pearson Education, Inc.Chapter 3 13 14. MeanwhileBack in the Lab Marie & Pierre Curie studied radioactive stuff, like pitchblende, the ore fromwhich uranium was extracted. Pitchblende was strangely more radioactive than the uranium extracted from it.They deduced that the pitchblende must contain traces of an unknownradioactive substance far more radioactive than uranium. Their work resulted in the identification of two new elements. The firstelement, they named "polonium," after Maries native country, Poland. Theother element they named "radium," for its intense radioactivity. Radiumbecame the initial industrial gamma ray source. The material allowedradiographs of castings up to 10 to 12 inches thick to be produced. The couple became victims of radiation poisoning. During World War II and the race to produce a nuclear weapon, much wasdiscovered about radioactive materials, and manmade isotopes becameavailable. Ultimately the United States began their Manhattan Project. 2013 Pearson Prentice Hall, Inc.3/14 15. Three Types of Radioactivity 2013 Pearson Education, Inc. Chapter 3 15 16. Three Types of Radioactivity 2013 Pearson Education, Inc. Chapter 3 16 17. Rutherford Gold Foil ExperimentIn 1911, Ernest Rutherford published a paper in which hedetailed his Gold Foil Experiment. Using an apparatussimilar to that shown below, Rutherford discovered theatomic nucleus.http://www.youtube.com/watch?v=XBqHkraf8iE 2013 Pearson Education, Inc.Chapter 317 18. Rutherford Gold Foil Experiment1) What were the details of the atomic model BEFORE this expt?2) What was Rutherfords hypothesis before the experiment?3) How did the results of the Gold Foil expt. Change/modify the model of the atom? 2013 Pearson Education, Inc. Chapter 3 18 19. Rutherfords Resultschanging the PPM 1) What does this picture tothe left tell us about theatomic model post-Rutherford? 2) What evidence fromRutherfords expt suggestsamendments be made tothe PPM? 3) What is a good name forthe Rutherford Model? 2013 Pearson Prentice Hall, Inc. 3/19 20. Rutherfords ModelHow did Rutherfords Model improve upon Thomsons Model? What were the weaknesses with Rutherfords Model? Limitations of Classical Mechanics in working with sub-atomic particles Success and limitations of Rutherford model of an atom:1. It showed for the first time, that the atomic volume is mostly devoid of mass except at its tiny positively charged center.2. The classical theory predicts the accelerating electron in orbit to radiate electromagnetic energy. One would think, the electron that radiates would decrease its total energy and fall spiraling into the nucleus collapsing the atom. Whereas we know the atoms to be stable. 21. Subatomic Particles 2013 Pearson Education, Inc.Chapter 321 22. Atomic Structure Atomic number: The number of protons in a nucleus. Mass number: The sum of protons and neutrons in a nucleus. Nuclide Notation: 2013 Pearson Education, Inc. Chapter 322 23. IsotopesIsotopes have the same atomicnumber, but have different mass numbers(same number of protons, but differentnumber of neutrons). 2013 Pearson Education, Inc.Chapter 3 23 24. Electron Arrangement:The Bohr ModelFlame tests: Different elements give different colorsto a flame. 2013 Pearson Education, Inc. Chapter 324 25. Toward a Quantum Model of the Atom Classical Physics, (Mechanics), and Rutherfords nuclear model cannotexplain chemical properties of elements. Experiments with radiant energy, light, reveal interesting properties ofmatter perhaps related to the atomic model. What is the visible spectrum? IR? UV? line spectra? emission spectra? A cool web site:http://jersey.uoregon.edu/vlab/elements/Elements.html 26. Electron Arrangement:The Bohr ModelContinuous spectra:When light emitted froma solid substance ispassed through a prism, itproduces a continuousspectrum of colors. 2013 Pearson Education, Inc. Chapter 3 26 27. Electromagnetic Spectrum Visible spectrum range Planks equation, E=hc/(lambda) h=6.626 x 10-34 Js lambda=wavelength C=3.00 x 108 m/sec Practice Problem 3.24, pp 96 28. Electromagnetic Radiation:LightEnergy? E=hc/ E = energy h = Plancks constant = 6.626 x 10-34 Js = wavelength Q: What is wavelength? c = 3.00 x 108 m/s Questions: 1. What does this equation allow you to do? 2. How are E and related? Explain. c = = frequency Question: 1. What is frequency? Explain. 2. Practice Problem 4.3; pp 122 29. Will the Real Niels Bohr Please Stand Up? The Energy of Electrons is Quantized! Electrons may have only particular, discrete amounts of energy! Explain how these statements relate to the hydrogen spectrum shownbelow! Hint: Why are there black gaps between the solid colored vertical linesin the hydrogen spectrum? (There do not appear to be intermediateamounts of energy!) In other words the spectrum in NOT continuous. Below you can see an emission line spectrum of hydrogen. It wasproduced by exciting a glass discharge tube of hydrogen gas with about5000 volts from a transformer. It was viewed through a diffractiongrating with 600 lines/mm. The colors cannot be expected to be accuratebecause of differences in display devices 30. The 5th Solvay Conference: Brussels from23-29 October 1927.Back row: A Piccard, E Henriot, P Ehrenfest, Ed Herzen, Th De Donder, E Schroedinger, E Verschaffelt, W Pauli, W Heisenberg, R H Fowler, L Brillouin. Middle Row: P Debye, M Knudsen, W L Bragg, H A Kramers, P A M Dirac, A H Compton, L de Broglie, M Born, N Bohr. Front Row: I Langmuir, M Planck, Mme Curie, H A Lorentz, A Einstein, P Langevin, Ch E Guye, C T R Wilson, O W Richardson. 31. Were Getting a New Deal for Physics! Classical Physics: Objects may have any energy! Quantum Physics: Objects, e.g., electrons, may have only specific energies Hmmm.so lets see, when the car accelerates, it is accelerating in a quantum manner, by set, specific amounts of speed, not in a smooth linear manneruhhisnt that a little herky-jerky?http://www.nhra.com/video/default.aspx 32. Eureka! Classical Physics works forobjects you can see, like bigobjects. Quantum Physics works todescribe the behavior ofobjects too small to observe, TylerBeani.e., sub-atomic particles---electrons!Hey Bob, Toby looks so cute when hecomprehends quantum mechanics. 33. The Bohr Model: BackgroundIn 1913 Niels Bohr came towork in the laboratory of ErnstRutherford. A few years earlierRutherford discovered the nuclearmodel of the atom. He asked Bohrto work on this model since hebelieved that there were someproblems with the model.According to the physics of thetime, Rutherfords nuclear atomshould have an extremely shortlifetime. Bohr thought about thisproblem and knew of the emissionspectrum of hydrogen. He quicklyFoiling the Nazis!! realized that the two problemshttp://crescentok.com/staff/jaskew/ISR/chemis were connected and after sometry/aquaregia.htm thought came up with the Bohrmodel of the atom. Bohrs modelof the atom revolutionized atomicphysics. 34. Electron Arrangement:The Bohr ModelLine spectra: Whenlight from a gaseoussubstance is passedthrough a prism, itproduces a linespectrum. 2013 Pearson Education, Inc. Chapter 3 34 35. Hydrogen gas, Discharge Tube, Pink Light Why does the gas glow pink when Mr. Bean turns on the generator? Why does the pink light separate into distinctly different colored lines in a hydrogen line spectrum? Do excited hydrogen atoms emit energy? light? 36. Emission of Light = Relaxation Energy An electron in an excited state can release energy in the formof light that corresponds to visible wavelengths that we see inthe hydrogen line spectrum. This emitted energy is called relaxation energy. There are many relaxation energies that correspond towavelengths that are outside the visible spectrum: 37. Balmer et al:1. The visible hydrogen spectral lines are in the 380nm-750nm range in what is called the Balmer series.2. Other energies are released for different transitions, e.g., n=5 to n=1, etc. that correspond to wavelengths beyond the visible spectrum.3. Given all the energy transition possibilitiesthis gets pretty complicated. New image what this would be like for a multiple electron atom! 38. Electron Arrangement:The Bohr ModelQuantum: A tiny unit of energy produced orabsorbed when an electron makes a transition fromone energy level to another. 2013 Pearson Education, Inc. Chapter 338 39. Electron Arrangement:The Bohr ModelWhen electrons are in the lowest energy state, they aresaid to be in the ground state.When energy from a flame or other source is absorbedby the electrons, they are promoted to a higher energystate (excited state).When an electron in an excited state returns to a lowerenergy state, it emits a photon of energy, which may beobserved as light. 2013 Pearson Education, Inc. Chapter 339 40. The Bohr Model FOUR Principles:1. Electrons assume only certain orbits around the nucleus. These orbits are stable and called "stationary" orbits.2. Each orbit has an energy associated with it. For example the orbit closest to the nucleus has an energy E1, the next closest E2 and so on.3. Light is emitted when an electron jumps from a higher orbit to a lower orbit and absorbed when it jumps from a lower to higher orbit.4. The energy and frequency of light emitted or absorbed is given by the difference between the two orbit energies, e.g.,E(light) = |Ef - Ei|E(light) = hNote: = frequency; E = hc/; = hc/E; c = h= Plancks constant = 6.627x10-34 Jswhere "f" and "i" represent final and initial orbits and EWith these conditions Bohr was able to explain the stability of atoms as well as the emission spectrum of hydrogen. According to Bohrs model only certain orbits were allowed which means only certain energies are possible. These energies naturally lead to the explanation of the hydrogen atom spectrum: Bohrs model was so successful that he immediately received world-wide fame. Unfortunately, Bohrs model worked only for hydrogen. Thus the final atomic model was yet to be developed. 41. Toward a Bohr or Quantum Model Orbits, shells, get largeras the principal quantumnumber, (n), increases. Electrons in the n=1 orbithave the lowest energy,(ground state). Electrons inorbits where n is larger havemore energy. Each shell can hold amaximum of 2n2 electrons.Hmmmwhat are theelectron capacities for thefirst four shells? 42. Building a Bohr AtomA Bohr Model Draw a Bohr model of asodium atom: 23 Na 111) Draw the nucleus, indicate #p and #n2) Determine the #e-s in the atom.3) Fill shells to their capacity with e-s starting with n=1, (lowest energy, most stable), to 43. The Mystery of Periodicity &Line Spectra Explained!!! The number of electrons in the valence shell of an atom isequal to the Roman numeral group for the representativeelementsEureka! Uuhwhats a valence shell? 44. Bohr: Periodicity Bohr model shows that atoms of elements in thesame groups, (families), of the representativeelements have identical electron configurations intheir valence shells! Hencestrong evidence to support a direct cause-effect relationship between similar chemicalproperties of elements in the same groups ofrepresentative elements and their common valenceshell electron configurations! 45. Bohr: Line Spectra It explained why line spectra exist. Bohrs mathematical model using Plancks resultscan reproduce the hydrogen line spectrum. Bohrs mathematic model quantified the energies ofeach line in the hydrogen spectrum. The differences in the energies between each shellcorrespond to the equivalent energies associated witheach spectral line in the hydrogen line spectrum. http://www.youtube.com/watch?v=-YYBCNQnYNM&feature=related 46. Electron ArrangementEnergy states or levels are sometimes called shells. 2013 Pearson Education, Inc. Chapter 3 46 47. Electron Arrangement:The Quantum ModelThe Quantum model of the atom is a probability-based model. It is composed of principal energylevels, sublevels, and orbitals. 2013 Pearson Education, Inc. Chapter 3 47 48. No Model is Perfect!!!! Predicted Helium line spectrum did not match upwith observed helium line spectrum. Bohrs mathematical model could not correctlypredict any spectrum beyond Hydrogen. Improved spectroscopes revealed that the Hydrogenline spectrum was not so simple. What was thought to be single vertical lines in thespectrum were in fact closely spaced compound linesthat appeared previously as single, bold spectral line. 49. Electron Arrangement:The Quantum ModelPrincipal energy levels (shells): Roughly correlate tothe distance that an electron is from an atoms nucleus.Sublevels (subshells): Each principal energy level (n) isdivided into n sublevels.Orbitals: Orbitals are regions in space that represent ahigh probability of locating an electron. Each sublevelhas one or more orbitals. 2013 Pearson Education, Inc. Chapter 3 49 50. And then there were Sub-Shells! The existence of multiple lines withina single, bold spectral line wasexplained by the existence of sub-shells within a shell. Sub-shells are closely spaced inenergy and size. The principle quantum numbercorresponds to the number of sub-shells in each shell. Electron capacity for each sub-shell: s=2 p=6 d = 10f = 14 s pdf in order of increasingenergy and size But then there is this PotassiumProblem! 51. Electron Arrangement:The Quantum Model 2013 Pearson Education, Inc. Chapter 3 51 52. Electron Arrangement:The Quantum Model 2013 Pearson Education, Inc. Chapter 3 52 53. Modern Quantum Mechanical Model of the Atom Schredinger: Wave Mechanicsthe idea that electrons have wavelike behavior Heisenberg: UncertaintyPrinciplethe idea that you canestimate the probable location ofan electron in an atom. Sub-shells correspond to probablelocations, (and energies), forelectrons. Sub-shells have shapes: orbitals:s, p, d and f 54. MQMM The Modern QuantumMechanical Model: Retains Rutherfords tiny,massive, positive nucleus Retains Bohrs idea of quantizedenergy of electrons http://www.upscale.utoronto.ca/GeneralInterest/Harrison/BohrModel/BohrModel.html http://www.upscale.utoronto.ca/GeneralInterest/Harrison/BohrModel/Flash/BohrModel.htmlHeisenberg & Pauli often communicated in secret about thesubtleties of the Uncertainty Principle and the Exclusion This movie, QuantumPrinciple. It was important to keep everything Top Secret Mechanics, is long, but wellworth it. http://www.youtube.com/watch?v=Nv1_YB1IedE&feature=BFa&list=LPWBNBv75jtYM 55. Which one is Heisenberg?The more precisely the position is determined, theless precisely the momentum is known in thisinstant, and vice versa.--Heisenberg, uncertainty paper, 1927Check it outinteresting.http://www.aip.org/history/heisenberg/p08.htm55 56. Electron Arrangement:The Quantum ModelElectronconfigurations: Allowus to represent thearrangement of theelectrons in an atom. 2013 Pearson Education, Inc. Chapter 3 56 57. Electron Arrangement:The Quantum Model 2013 Pearson Education, Inc. Chapter 3 57 58. Electron Arrangement:The Quantum Model The textbook order-of-filling chart: (Merely OK) 2013 Pearson Education, Inc. Chapter 358 59. Electron Configurations Order of Filling (Easier): Write an expandedelectron configurationfor an atom of lead. Now, write the noblegas shortcutconfiguration for anatom of lead.An easier shortcut method forfilling sub-shells. 60. Electron Arrangement:The Quantum Model 2013 Pearson Education, Inc. Chapter 3 60 61. Electron Configurations and thePeriodic TableThe periodic table is considered by many to be the mostpredictive tool in all of chemistry.It is composed of vertical columns called groups (orfamilies) and horizontal rows called periods.Can you name and groups? Which ones? How are theydenoted? 2013 Pearson Education, Inc. Chapter 361 62. Electron Configurations and thePeriodic TableGroups (families): Vertical columns in the periodictable. Groups contain elements with similar chemicalproperties.Periods: Horizontal rows in the periodic table. Elementsin a period demonstrate a range of properties frommetallic (on the left) to nonmetallic (on the right). 2013 Pearson Education, Inc. Chapter 3 62 63. Electron Configurations and thePeriodic TableValence electrons: Valence electrons are the electrons in theoutermost principal energy level of an atom. These are the electrons that are gained, lost, or shared in a chemical reaction. Elements in a group or family have the same number of valence electrons. 2013 Pearson Education, Inc.Chapter 363 64. Electron Configurations and thePeriodic TableSome groups in the periodic table have special names:Alkali Metals: Group 1A Valence electron configuration: ns1Alkaline Earth Metals: Group 2A Valence electron configuration: ns2Halogens: Group 7A Valence electron configuration: ns2np5Noble Gases: Group 8A Valence electron configuration: ns2np6Get it?...Neon 2013 Pearson Education, Inc. Chapter 3Trees64 65. Electron Configurations and thePeriodic Table Metals, Nonmetals, and Metalloids: Metals Metallic luster, conduct heat and electricity, malleable, and ductile. Examples are sodium and copper. Name the family and period for both elements. Nonmetals Dull luster, nonconductors, and brittle in the solid state. Examples are sulfur and bromine. Name the family and period for both of these elements. Metalloids Demonstrate properties of both metals and nonmetals.Auric GoldfingerExamples are silicon and arsenic. Name the family andperiod for both elements. 2013 Pearson Education, Inc. Chapter 365 66. Electron Configuration Practice: Write the expanded AND noble gasabbreviated electron configurations for: Cu Na As S Br Si 2013 Pearson Prentice Hall, Inc. 3/66 67. Periodic Trends 2013 Pearson Prentice Hall, Inc. 3/67 68. Electron Configurations and the Periodic Table 2013 Pearson Education, Inc. Chapter 3 68 69. The Song of the Elements! Memorize this song. If Tomyou sing it in a schoolLehrerassembly with aanotherpianist andlegend..accompanied by ourclass then You win a $100 giftcertificate to Sushidinner in Quincy. http://www.youtube.com/watch?v=aPq3SEteEJc