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Unformatted text preview: 1 Chapter 12: Quantum Mechanics and Atomic Theory o Electromagnetic Radiation o Quantum Theory o Particle in a Box o The Hydrogen Atom o Quantum Numbers o Orbitals o Many Electron Atoms o Periodic Trends 1 Big Idea: The structure of atoms must be explained using quantum mechanics, a theory in which the properties of particles and waves merge together. Chapter 12: Quantum Mechanics and Atomic Theory Electromagnetic Radiation Electromagnetic Radiation: Consists of oscillating (time-varying)electric and magnetic fields that travel through space at 2.998 10 8 ? ? (c = speed of light) or just over 660 million mph. 2 Note: All forms of radiation transfer energy from one region of space into another. Examples of Electromagnetic Radiation: Visible light Radio Waves X-Rays Chapter 12: Quantum Mechanics and Atomic Theory Electromagnetic Radiation Wavelength (): Is the peak-to-peak distance. Amplitude: Determines brightness of the radiation. Frequency (): The number of cycles per second ( 1 ? = 1 ? ). 3 Note: Changing the wavelength changes the region of the spectrum (i.e. x-ray to visible). Chapter 12: Quantum Mechanics and Atomic Theory Electromagnetic Radiation 4 Chapter 12: Quantum Mechanics and Atomic Theory Quantum Theory If white light is passed through a prism, a continuous spectrum of light is found. However, when the light emitted by excited hydrogen atoms is passed through a prism the radiation is found to consist of a number of components or spectra lines. 5 Chapter 12: Quantum Mechanics and Atomic Theory Quantum Theory Black Body: An object that absorbs and emits all frequencies of radiation without favor. Heated Black Bodies = . ? ? = . ? 6 Note: max is the most prevalent wavelength not the longest wavelength. 2 Chapter 12: Quantum Mechanics and Atomic Theory Quantum Theory Theory Scientists used classical physics arguments to derive an expression for the energy density (Rayleigh Jens Law). ???? ?? 4 The Problem With Explaining Black Body Radiation Using Classical Mechanics Classical mechanics put no limits on minimum wavelength therefore at very small , ? would be a huge value even for low temperatures. 7 Chapter 12: Quantum Mechanics and Atomic Theory Quantum Theory Max Plank: Proposed that the exchange of energy between matter and radiation occurs in quanta, or packets of energy. His central idea was that a charged particle oscillating at a frequency , can exchange energy with its surroundings by generating or absorbing electromagnetic radiation only in discrete packets of energy....
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This note was uploaded on 01/18/2012 for the course CHEM 1B taught by Professor Watts during the Winter '08 term at UCSB.
- Winter '08