Chapter 7 notes

Chapter 7 notes - Chapter 7 Quantum Theory Atomic Structure...

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Slide No. 1 Chapter 7: Quantum Theory & Atomic Structure ± Overview ² The reason we study quantum theory and atomic structure is so that we can understand how atoms and molecules are put together (bonding) and how matter interacts with light (spectroscopy). ± Light ² Wave and Particle Nature ± Atomic Spectra ² Absorption and Emission Spectra ² Bohr Model of the Hydrogen Atom ± Quantum Mechanical Model of the Hydrogen Atom ² Schrödinger Equation ² Quantum numbers and Atomic Orbitals ± Reading: 7.1, 7.2, 7.4 ± Homework Problems: 7(8), 9(10), 13(15), 23(24), 27(28), 29(30), 49(50), 55(56), 57(58), 59(60) Lecture Outline Slide No. 2 7.0 Review of the Atom ± Nucleus ² contains positively charged ______ ² contains neutrons – affect weight and stability ² tiny size but contains nearly all of the atomic mass ± Electrons ² Orbit the nucleus in a diffuse "cloud" of particles ² The location and movement of electrons largely determines the _________ of atoms within molecules. ² Until now, we have no idea of what the electrons are doing. Are they flying in circular orbits? Are they stationary? Quantum mechanics will answer that question. ± Early atomic theory ² Focused primarily on interactions of atoms with light ² The theory of _____ developed at the same time
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Slide No. 3 ± Light ² Broader definition includes all electromagnetic _________ from radio- through gamma- rays. ± Light has Wave Characteristics ² speed, c = 3.0 x 10 8 m/s ² wavelength, λ • crest-to-crest distance • mm, cm, m ² frequency, ν • "per second", s -1 , hz ± Frequency and Wavelength ² c = λν ² c = 3 x 10 8 m/s in a vacuum (slightly slower in other media) ² As λ increases, ν decreases λ Memorize c = λν The Wave Nature of Light 7.1 The nature of light Slide No. 4 Light Amplitude ± Amplitude determines light intensity , not light energy ± A way to remember this is that in wave sounds amplitude determines sound volume , not sound pitch ² Lower amplitude ² Higher amplitude 7.1 The nature of light (same energy because they have same wavelength)
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Slide No. 5 The Electromagnetic Spectrum ± Light (electromagnetic radiation) spectrum Low Frequency High Frequency 400 nm 700 nm Low Energy High Energy 7.1 The nature of light Long Wavelength Short Wavelength Slide No. 6 The Particle Nature of Light ± Unsolved problems that led to the Quantum Theory (classical (Newton) mechanics could not explain them) ² Blackbody radiation (Planck solved it and got the Nobel Prize (1918)) ² The photoelectric effect (Einstein solved it and got the Nobel Prize (1921)) ² Line spectra of gases (Bohr solved it and got the Nobel Prize (1922)) ± 1900’s – Planck – light is also particle-like. ² Photon = “particle” of electromagnetic energy ² When an atom _______ energy, it absorbs one photon ² Photon energy is given by E = h ν = hc/ λ ² h = Planck’s Constant = 6.626x10 –34 (J•s)/(photon) – the “per photon” is usually omitted from the units Memorize E = h ν = hc/ λ ± Light Concepts – True or False a) As the wavelength of light increases, its energy decreases.
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This note was uploaded on 03/31/2008 for the course CHEM 1035 taught by Professor Jgdillard during the Fall '07 term at Virginia Tech.

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Chapter 7 notes - Chapter 7 Quantum Theory Atomic Structure...

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