Chapter 6: Electronic Structure of AtomsConcept CheckReview: Light Behaves Like a Wave, or Does it?Practice ProblemAtomic Structure 1: Electron EjectionAtomic Structure 2: Line Spectra of AtomsThe Bohr Model of the H Atom (1913)The Bohr Model of the H Atom (1913) Predicts Line SpectraThe Bohr Model of the H Atom (1913) Predicts Electron Ejection EnergyPractice ProblemLecture ProblemWave Nature of MatterConsequences of the Wave Nature of Electrons in AtomsOrbitals and Quantum NumbersQuantum Numbers are like Train Tickets…What Should You Know?What Should You Know?Chapter 6: Electronic Structure of AtomsCH110 FA10 SAS 1By the end of Lecture 6 you should know:wavelength and frequency of light, dual nature of light, electronic transitions and line spectraBohr modelMatter acts as wavesHeisenberg Uncertainty PrincipleElectronic transitions of orbitalsQuantum numbers (n, , m, ms)Orbitals: their shapes and energiesOrbitals and atoms with many electronsSpin quantum number (ms): Pauli Exclusion Principle and Hunds RuleElectron Configurations using the periodic tableWhat is the structure of an atom?What are the properties of atoms?Remember: structure affects function!Where are the electrons located? What is the energy of an electron?KEY QUESTIONS: THE BIG PICTUREConcept CheckCH110 FA10 SAS 2Understanding electromagnetic energy led toquantum theory(it explains what we observe) which led toatomic structureand predictselectron configurationsand explainsperiodic trends of the elementsReview: Light Behaves Like a Wave, or Does it?CH110 FA10 SAS 3• Light and other electromagnetic radiationbehaves as a ______• Light and other electromagnetic radiation behaves as a ________ with kinetic energy• Light behaves like a particle with a wavelength called a ______c = E = Speed of lightIn a vacuumKineticEnergyE =Practice ProblemCH110 FA10 SAS 4What is the total energy of one mole of green photons (wavelength equal to 523 nm)?A. 3.80 x 10-19kJ B. 6.32 x 10-43kJ C. 2.29 x 105kJD. 229 kJE. 632 kJ• When electrons are emitted, the ________emitted is proportional to the ___________• The energy of the light follows this rule:• NO e-will be emitted if ________Atomic Structure 1: Electron EjectionCH110 FA10 SAS 5Albert Einstein: The Photoelectric Effect.direct observation of quantum effects!Light in Electrons outmetalAlbert Einstein 1921 Nobel Prize in PhysicsObservation: Electrons are emitted by metal only if light has frequency greater than certain minimum value.Ek= KE of emittedphotoelectronCH110 FA10 SAS 6Atomic Structure 2:Line Spectra of AtomsE3E2E1excited states (_______ energies)ground state = (________ energy)EnergyWhat if hν isn’t enough to eject an e-?• Absorption: energy of photon causes energy of electron to ________• Emission: electron ______ energy by giving off a photon• Observation: Only certain __________of light are absorbed emitted• Conclusion: the electrons in atoms can only have certain _________ :The Bohr Model of the H Atom (1913)CH110 FA10 SAS 7Note: Orbit energy in the Bohr model is negative, so it must correspond to energy needed to put electron into the orbit.Neils Bohr, 1922 Nobel Prize in Physics, really, not such a bad guyTwo Postulates:1. Energy levels are quantized(e-can only have specific energies in an atom).2. Transitions are quantized: only certain discrete energy changes are possible.n = 1, 2, ...RH Rydberg constant= 2.180 x 10–18Jn = principal quantum #Allowed Energy Levels: “Orbits”En = -RH(1/n2)The Bohr Model of the H Atom (1913)Predicts Line SpectraCH110 FA10 SAS 8n = 4n = 1n = 2n = 3etc. . . .Transitions are accompanied by absorption or emission of light:∆E = Efinal– EinitialRHni2If nf> nithen ∆E is + ______ photonIf nf< nithen ∆E is – ______ photon–= 1nf21∆E =hνPredicts the H-atom spectrum EXACTLYThe Bohr Model of the H Atom (1913)Predicts Electron Ejection EnergyCH110 FA10 SAS 9n=1n=2n=3n=∞n = 1n = 2n = 3n = 4E/RH= E/RH= E/RH= E/RH= ∆E = hν = RHni2–1nf21Coulomb’s Law:n = ∞E/RH=Practice ProblemCH110 FA10 SAS 10Which of the following transitions in an H atom results in the emission of the highest energy photon?1. n=1 → n = 62. n=6 → n = 33. n=3 → n = 64. n=1 → n = 45. n=6 → n = 1Lecture ProblemCH110 FA10 SAS 11For the H atom, what is the wavelength of light emitted for the ni= 2 → nf= 1 electronic transition?1. 574 nm2. 472 nm3. 219 nm4. 122 nm5. 101 nmWave Nature of MatterCH110 FA10 SAS 12Wave properties λν = cParticle properties E = hνDual nature of light:de Broglie (1924) asked the following:If light has a duality, why not matter too ?λ =hm·vm·v is ___________Because λ ∝ 1/m the effects are onlyobservable for extremely _____ masses• De Broglie wavelength• Wave properties of electrons areconfirmed experimentally:Electron microscopeThe Bohr model explained some experimental data for the hydrogen atom, but it failed for other atoms…Consequences of the Wave Nature of Electrons in AtomsCH110 FA10 SAS 13Electrons have wave properties:• The mass of the electron is well known• Uncertainty in knowing the exact position or __________ of an electron (Heisenberg Uncertainty Principle)• Can calculate the _________ of knowing the location of an electron and know it’s ______Not Orbits, but OrbitalsErwin Schrödinger, 1933 Nobel Prize in PhysicsWerner Heisenberg, 1932 Nobel Prize in PhysicsOrbitals and Quantum NumbersCH110 FA10 SAS 14Overview:1. Principal quantum number n=2. Azimuthal quantum number =3. Magnetic quantum number m=4. Spin quantum number ms =Bohr againQuantum Numbers are like Train Tickets…CH110 FA10 SAS 15Figure from Moore, Stanitski, Jurs (2005) Chemistry: The Molecular Science; Thomson Brooks/ColeWhat Should You Know?CH110 FA10 SAS 16Properties of Electromagnetic Radiation:1. What is spectroscopy? A continuous spectrum? A line spectrum?2. What is the relationship of wavelength to frequency? Of E to λ? Of E to ν?3. What are the types of EMR? The relative order of wavelength? The relative order of colors and range of wavelength in the visible spectrum?4. What are the conversion rules for the various units we have discussed?5. What wavelengths have higher frequency? Higher energy?Particle Behavior of Light:1. Calculate the energy of a photon or mole of photons.2. Can you calculate Ebof an electron?3. What is a “quantum”?What Should You Know?CH110 FA10 SAS 17Bohr Model of the Hydrogen Atom1. How does Bohr describe an atom?2. Calculate the