chapter 6 Electronic structure of Atoms

chapter 6 Electronic structure of Atoms - Chapter 6 Chapter...

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Chapter 6 Chapter 6 Electronic Structure of Atoms Electronic Structure of Atoms
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Our goal: Understand why some substances behave as they do. For example: Why are K and Na reactive metals? Why do H and Cl combine to make HCl? Why are some compounds molecular rather than ionic? Atom interact through their outer parts, their electrons. The arrangement of electrons in atoms are referred to as their electronic structure. Electron structure relates to: Number of electrons an atom possess. Where they are located. What energies they possess. Electronic Structure Electronic Structure
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Study of light emitted or absorbed by substances has lead to the understanding of the electronic structure of atoms. Characteristics of light: All waves have a characteristic wavelength, λ , and amplitude, A . The frequency, ν , of a wave is the number of cycles which pass a point in one second. The speed of a wave, v , is given by its frequency multiplied by its wavelength: For light, speed = c . The Wave Nature of Light The Wave Nature of Light λν = c
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Identifying Identifying λ λ and and ν ν
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Modern atomic theory arose out of studies of the interaction of radiation with matter. Electromagnetic radiation moves through a vacuum with a speed of 2.99792458 × 10 -8 m/s. Electromagnetic waves have characteristic wavelengths and frequencies. Example: visible radiation has wavelengths between 400 nm (violet) and 750 nm (red). Electromagnetic Radiation Electromagnetic Radiation
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The Electromagnetic Spectrum The Electromagnetic Spectrum
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The yellow light given off by a sodium vapor lamp used for public lighting has a wavelength of 589 nm. What is the frequency of this radiation? Class Guided Practice Problem Class Guided Practice Problem λν = c Class Practice Problem A laser used to weld detached retinas produces radiation with a frequency of 4.69 x 10 14 s -1 . What is the wavelength of this radiation?
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Planck : energy can only be absorbed or released from atoms in certain amounts “chunks” called quanta. The relationship between energy and frequency is where h is Planck’s constant (6.626 × 10 -34 J.s). To understand quantization consider walking up a ramp versus walking up stairs: For the ramp, there is a continuous change in height whereas up stairs there is a quantized change in height. Quantized Energy and Photons Quantized Energy and Photons ν h E =
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Planck’s theory revolutionized experimental observations. Einstein: Used planck’s theory to explain the photoelectric effect. Assumed that light traveled in energy packets called photons. The energy of one photon: The Photoelectric Effect The Photoelectric Effect ν h E =
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Calculate the energy of a photon of yellow light whose wavelength is 589 nm. Class Guided Practice Problem
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This note was uploaded on 02/20/2011 for the course CHEM 101 taught by Professor John during the Spring '11 term at Caldwell College.

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chapter 6 Electronic structure of Atoms - Chapter 6 Chapter...

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