Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21The Spectrum of Electromagnetic RadiationSlide 23Slide 24Electromagnetic RadiationSlide 26Slide 27Slide 28The Photoelectric Effect - IThe Photoelectric Effect - IISlide 31Chapter 7: Quantum Theory and Atomic StructureThe Nature of LightAtomic SpectraThe Wave - Particle Duality of Matter and EnergyThe Quantum - Mechanical Model of the AtomChapter 7 - Quantum Theory of the AtomProblems: 19, 23, 27, 31, 33, 37, 39, 43, 45, 47,49, 51, 53, 57, 63, 65, 67, 71, 75, 77, 81, Read the entire chapterAnswer all the Review Problems.What are the electrons doing in the atom?Why do atoms form ions and molecules?Why do hydrogen and oxygen “stick” together to form water?To understand these questions, we need to understandthe electronic structure of the atomElectronic structure referes to the way the electrons are arranged in an atomAtoms are the basic building blocks of matter.They are the smallest units of an element that can combine with other elements (that is, take part ina chemical reaction.Structure of the AtomThe simple view: only three subatomic particleshave a bearing on chemical behavior.Protons, Neutrons and ElectronsProton is a nuclear particle having a positive chargeequal to that of the electron and a mass more that 1800 times that of the electrons.Neutron is a nuclear particle having a mass almost identical to that of the proton butwith no electric chargeElectron is a negatively charged particle withthe negative charge equal to that of the proton.Protons and neutrons reside together in a very small volume within the atom known as the nucleus.Most of the rest of the atom is space in whichthe electrons moveneutronsprotonselectrons1. Each element is composed of extremely small particles called atoms.2. All atoms of a given element are identical.3. Atoms of different elements have different properties (including different masses).4. Atoms and elements are not changed into differenttypes of atoms by chemical reactions.5. Compounds are formed when atoms of morethan one element combine.We Know: Atoms (elements) are the basic unit of chemical stucture and are made of protons, neutronsand electrons (simplification) Compounds are made up of elements (atoms) in difinite proportions. Compounds are also called Molecules.6C12.01114A2Parts of the Periodic TableGroupPeriodAtomic symbolAtomic numberAtomic mass(amu)The present theory of the electronic structure of the atomstarted with an explanation of the colored light producedin hot gases and flamesThis means we need to know something about the natureof light and radiant energyRadiant energy is electromagnetic radiation: light, X raysAll types of radiant energy move through a vacuum atthe speed of light (c) 3.00 x 108 m/sAll radiant energy has wavelike characteristicsA wave is periodic in nature and can be characterizedby its wavelength and frequencyis thedistance between any two adjacent identical points of a waveFrequency (- the number of wavelengths of that wavethat pass a fixed point in one unit of time (usually 1 sec.)Short wavelengthHigh FrequencyLong wavelengthlow frequencyWavelength and frequency are relatedWhat else do we know?We said that all types of radiant energy move througha vacuum at 3.0 x 108 m/sWe know that   is the distance between identical pointson successive wavesWe know that  is the number of times per second thatone complete wavelength passes a given point.So:c = The yellow light given off by a sodium lamp has a wavelength of 589 nm. What is the frequency of this radiation?c = c/ c = 3.0 x 108 m/s = 3.0 x 108 m/s589 nmx 109 nm1 m= 5.09 x 1014/sElectromagnetic radiation (light) consists of occilationsin electric and magnetic fields that can travel throughspace. These occilations can be characterized in termsof wavelength and frequencyThe range of frequencies and wavelengths of electromagnetic radiation is called theelectromagnetic spectrumThe visible spectrum 400 nm (violet) to 800 nm (red)Fig. 7.3The Spectrum of Electromagnetic Radiation•The wavelength of visible light is between 400 and 700 nanometers•Radio, TV , microwave and infrared radiation have longer wavelengths (shorter frequencies), and lower energies than visible light.•Gamma rays and X-rays have shorter wavelengths (larger frequencies), and higher energies than visible light!Fig. 7.1Fig. 7.2Electromagnetic Radiation•WAVELENGTH - The distance between identical points on successive waves. (  )•FREQUENCY - The number of waves that pass through a particular point per second. ()•AMPLITUDE - The vertical distance from the midline to a peak, or trough in the wave.cCalculation of Frequency from WavelengthProblem: The wavelength of an x-ray is 1.00 x10 -9 m or 1 nm, what is the frequency of this x-ray? If the wavelength of long-wavelength electromagnetic radiation is 7.65 x 104 m, what is the frequency of this long-wavelength radiation used to contact submerged nuclear submarines at sea?Plan: Use the relationship between wavelength and frequency to obtainthe answer. wavelength x frequency = speed of light!Solution:frequency(cycles/sec) = speed of light wavelength(m)frequency = = 3.00 x 1017 cycles/sec3.00 x 108 m/s1.00 x 10 - 9 ma)b) frequency = = 3.92 x 103 cycles/s 3.00 x 108 m/s7.65 x 104 mDifferent Behaviors of Waves and ParticlesFig. 7.4The Diffraction Pattern Caused by Light Passing through Two Adjacent SlitsFig. 7.5The Photoelectric Effect - I•Below the threshold energy, nothing occurs !•Above the threshold, the kinetic energy of the ejected electrons is proportional to the frequency of the light.•Also, when above the threshold, as intensity of the light increases, so does the number of ejected electrons.•All metals experience this effect, but each has a unique threshold frequency.The Photoelectric Effect - II•Albert Einstein –Theorized Photons–Won Nobel prize - 1921•Photons have an energy equal to: E = h•h = Plank’s Constant, and is equal to:6.6260755 x 10 - 3 4JsecDemonstration of the Photoelectric EffectFig.